PREFACE

This book has the aim of providing an intelligible interpretation of the views expressed by St. Thomas Aquinas in his De Principiis Naturae and in his De Mixtione Elementorum. Together, these two brief works offer a remarkably clear, sophisticated, and in many ways convincing, account of the nature of physical things, in terms of a theory which combines composition out of matter and form with composition out of elements.

An interpretation is an attempt to bring out the meaning of a work by entering into it in a sympathetic way, i.e., by trying hard to understand what the author of the work is saying. And this, to me, means at least 1) trying to make as clear as possible the sense of the claims being made by the author, and 2) arguing as convincingly as possible either for them or against them, as each of them may require.

An interpretation is intelligible if it 1) squares with the observed facts, i.e., with what is given in sense observation and in introspection, 2) is free of internal inconsistencies, i.e., preserves the interconnections among ideas as given in analysis, and 3) is in principle capable of coping with objections, and with other interpretations, thereby illuminating its own positions.

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The aim of this book is not a scholarly one. There will be no attempt, therefore, to take into account the countless things which countless people have had to say about Aquinas on matter and form and the elements. Nor will there be any attempt to pursue in footnotes, or in appendices, or elsewhere, the generally uninteresting, and only remotely (if at all) relevant, asides which are too often pursued, and in overwhelming detail, in books of a scholarly sort.

The aim of this book, simply put, is to do some philosophy which is as genuine and as straightforward and as unencumbered as possible, using the words of Aquinas as a point of departure.

The translation of the De Principiis Naturae was made from the critical text of John J. Pauson;1 comparisons were made with the critical edition of Basil M.

Mattingly,2 and with the text of the Leonine edition.3 The translation of the De Mixtione Elementorum was made from the text as it appears in Spiazzi’s Opuscula Philosophica;4 this too was compared with the text of the Leonine edition.5 I have tried throughout, both in translating and in interpreting, to use ordinary and understandable English, and still keep the philosophical message intact.

Because the De Principiis Naturae (DPN) was a very early work of Aquinas (around 1252 or 1253) and the De Mixtione Elementorum (DME) a 1 Saint Thomas Aquinas, De Principiis Naturae. Introduction and Critical Text by John J. Pauson. Textus Philosophici Friburgenses, 2. Fribourg: Societe Philosophique, 1950.

2 Basil M. Mattingly, O.S.B. De Principiis Naturae of St. Thomas Aquinas. Critical Edition. Notre Dame, Indiana: University of Notre Dame. Doctoral Disser’ation, 1957.

3 De Principiis Naturae, ad fratrem Sylvestrum; Leonine edition, vol. 43, pp. 39–47.

4 Divi Thomae Aquinatis, Doctoris Angelici, Opuscula Philosophica. Cura et Studio P. Fr. Raymundi M. Spiazzi, O.P. Romae: Marietti, 1954: De Mixtione Elementorum ad Magistrum Philippum, pp. 155–156.

5 De Mixtione Elementorum, ad magistrum Philippum de Castro Caeli; Leonine edition, vol. 43, pp. 115–157.

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considerably later one (1273), and because the DME adds to what the DPN says about the elements, one should perhaps read and study the DPN before the DME.

And that is why the DPN is first in the arrangement of this book, in PART ONE, followed by the DME, in PART TWO; although my translation, and interpretation, of the DME was actually done before that of the DPN. My hope is that this will have no undesirable effects on those who read this book as arranged.

PART THREE reflects on what Aquinas has to say about matter and form and the elements, here and there throughout his many works, and in various contexts. This third part attempts to do at least the following: 1) to make as clear as possible how, according to Aquinas, these two kinds of composition, i.e., composition out of matter and form and composition out of elements, are related to one another and to the physical substances in which they are found, and 2) to see whether what he says can be accepted, i.e., to argue for or against his claims and arguments, as each of them may require.

PART FOUR looks at a mix of things from various sources, in an attempt to make clearer, to the extent that it can, both what Aquinas thought about the elements and what we today think about them: about the definition of ”element,” about the things that are listed as elements, about the causal role(s) of the elements, about the distinctive properties of each of the elements, about how various elements combine to form complex bodies (mixed bodies, in the languange of Aquinas), about whatever else suggests itself as important. The idea is that these two views, i.e., 1) that of Aquinas and 2) that of people today, might well, by appropriate comparisons and contrasts, shed some helpful and welcome light on one another.

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ACKNOWLEDGMENTS

For many of the good things in this book, I thank many generous and giving people, colleagues and students and friends. I thank James Cushing and William Shephard, professors of physics at the University of Notre Dame, for teaching me so much about quarks and leptons and the like, and for doing it with enthusiasm, clarity, and precision. I thank Gregory MacIsaac, doctoral student in philosophy at Notre Dame, for preparing the Index of Names and the Index of Subjects, and for doing it quickly, carefully, and thoroughly. I thank Coleen J. Hoover, our philosophy department’s administrative assistant, for laying out, and for making cameraready, the table of contents, the preface, the two indeces, and the copyright page, and for doing it willingly and with great skill.

And I thank Teresa, selfless wife of many years, and best friend, for being kind and understanding. But most of all for being so patient as a writer’s widow — which no doubt she would rather not have become — for a very long time.

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PART ONE—

DE PRINCIPIIS NATURAE

De Principiis Naturae1

Chapter One—

Generation and Corruption

In chapter one, Aquinas talks about many things: about what can exist, and what does exist; about what is simply (or period), and what is something or other; about matter and form; about prime matter and subject; about generation and corruption, both substantial and accidental; about form, both substantial and accidental; about privation; about art and nature. His comments seem to be aimed at making clear how to think and talk about change — in particular about change in the natural world.

Think and talk about it this way, he seems to be saying, because this is the way it is.

Being:

Potential and Actual; Substantial and Accidental

1. Nota quod quoddam potest esse licet non sit, quoddam vero est. Illud quod potest esse, dicitur potentia esse; illud quod iam est, dicitur esse actu. Sed duplex est esse: scilicet esse essentiale sive substantiale rei, ut hominem esse, et hoc est esse simpliciter; est aliud esse accidentale, ut hominem esse album, et hoc est esse aliquid.

Take note that some things can exist, though they do not, whereas others do indeed exist. Those which can exist are said to be potentially. Those which already do exist are said to be actually. And this in two ways. There is first the essential or

1 The title of this work could just as well have been De Principiis Generationis or De Principiis Rerum Naturalium. See below pp. 11–14, the section entitled, The meaning of

“nature” in the title: De Principiis Naturae, especially p. 14.

substantial existence of a thing, as for a man to be; and this is to be simply. There is secondly accidental existence, as for a man to be white; and this is to be something or other.

In 1., he observes that some things can exist, though they do not; and these are said to be potentially. Others things do exist; and these are said to be actually. What is the point of these remarks? one might ask. Aren’t they frustratingly obvious, and singularly uninformative? What intellectual advance, of even a minimally clarifying sort, is made by noting that what can exist is said (dicitur) to be potentially? Or that what does exist is said (dicitur) to be actually? Is “what is potentially” any clearer that “what can exist”? Is “what is actually” any clearer that “what does exist”? And does “dicitur” mean: is said in the ordinary, everyday language into which one is born? Or does it mean: is said in philosophical language, for philosophical purposes? And what difference, if any, would that make?

The point of these remarks seems to be to set the stage for a philosophical account of the observed fact of change in the physical or natural world. One way, perhaps the clearest and easiest way, to begin to think about physical or natural change is to think in terms of what can be and what is. For, a thing which is undergoing change both is and can be. It is or exists (and of course, since it is, it also is what it is); and simultaneously can be, though it yet is not, that which it is becoming. It could not be undergoing change if it did not exist (and exist as what it is); nor if it were not true to say of if that it can be (but is not) what it is becoming. To be (to be actually — what it is), to be able to be (to be potentially — what it is becoming), and not to be (not to be actually — what it is becoming) — these three provide a clear and easy way of beginning to think and to talk about matter (can be), form (is), and privation (is not). These three, i.e., matter, form, and privation — as Aquinas sees it, and as truth has it — are the three principles of nature, the three beginning points (principia), or sources, of the process of generation by which natural things are brought into existence.

Aquinas observes further, in 1., that the existence of a natural thing is of two sorts. There is, first, its essential or substantial existence; and this is only one. There is, secondly, its accidental existence; and this is more than one. For example, I exist — as what I am, i.e., a rational animal. This is my one essential or substantial existence. This is what I am (essential) as an ultimate existing subject (substantial). But, I am also five feet eight inches tall; white, knowledgeable, and virtuous; a father and a son, and taller than my daughter; I am being carried to my son’s house; before that I was at home, sitting on the sofa, at noon, and wearing comfortable slacks. These are among my many accidental existences. None of these is included in what I am essentially, i.e., in my one existence as an ultimate existing subject.

They are, one and all of them, added to, over and above, it. The ultimate existing subject is I — this rational animal. My being five feet eight inches tall, and white, and knowledgeable, etc. — no one of these is what I am as an ultimate existing subject. Neither is the collection of them what I am as an ultimate existing subject.

Furthermore, no one of them, nor the collection of them, is itself an ultimate existing subject.

Matter:

Prime Matter and Subject

2. Ad utrumque esse est aliquid in potentia. Aliquid enim est in potentia ut sit homo, ut sperma et sanguis menstruus; aliquid est in potentia ut sit album, ut homo. Et tam illud quod est in potentia ad esse substantiale, quam illud quod est in potentia ad esse accidentale, potest dici materia; sicut sperma hominis et homo albedinis. Sed in hoc differunt, quia materia quae est in potentia ad esse substantiale, dicitur materia ex qua; quae autem est in potentia ad esse accidentale, dicitur materia in qua. Item, proprie loquendo, quod est in potentia ad esse substantiale, dicitur materia prima; quod vero est in potentia ad esse accidentale, dicitur subiectum. Unde dicitur quod accidentia sunt in subiecto; non autem dicitur quod forma substantialis sit in subiecto. Et secundum hoc differt materia a subiecto, quia Page 4

subiectum est quod non habet esse ex eo quod advenit, sed per se habet esse completum; sicut homo non habet esse ab albedine. Sed materia habet esse ex eo quod sibi advenit, quia de se habet esse incompletum. Unde, simpliciter loquendo, forma dat esse materiae, accidens autem non dat esse subiecto, sed subiectum accidenti, licet aliquando unum ponatur pro alio, scilicet materia pro subiecto, et e converso.

There is something in potency to each of these ways of being. For example, there is something in potency to being a man, like sperm and menstrual blood; and there is something in potency to being white, like man. Both what is in potency to substantial existence, and what is in potency to accidental existence, can be called matter; like sperm, the matter of man; and man, the matter of whiteness. But they differ in this: the matter which is in potency to substantial existence is called the matter out of which; and that which is in potency to accidental existence is called the matter in which. Properly speaking, however, what is in potency to substantial existence is called prime matter; whereas what is in potency to accidental existence is called a subject. Whence it is said that accidents are in a subject; but it is not said that a substantial form is in a subject. And, it is according to this that matter differs from a subject: a subject does not have existence from that which comes to it; rather it has existence, complete existence, of itself; man, for example, does not have existence from whiteness. Matter, on the other hand, does have existence from that which comes to it, for of itself it has an incomplete existence. Whence, simply speaking, form gives existence to matter; whereas an accident does not give existence to a subject, but the subject to the accident; although at times one is used for the other, that is, matter for subject, and conversely.

In 2., Aquinas pursues the opening sentence of 1. “Take note,” he had said as he opened 1, “that some things can exist, though they do not, whereas others do indeed exist.” He points out here, as he begins 2., that just as there are two sorts of actual existence, there are correspondingly two sorts of potential existence. “There is something in potency to each of these ways of

being,” i.e., 1) to essential or substantial existence, or to being simply, like sperm and menstrual blood (it is really the ovum, as we know today, not the menstrual blood) to being a man; and 2) to accidental existence, or to being additionally something or other, like man to being white. And both of these can be called matter.

Sperm can be called the matter of man, and man the matter of whiteness. But each is a different sort of matter. This is why the matter which is in potency to substantial existence is called the matter out of which, to indicate that this matter is an ingredient of the ultimate existing subject; and why the matter which is in potency to accidental existence is called the matter in which, to indicate that this matter is not an ingredient of the ultimate existing subject, but rather the ultimate existing subject itself. The difference between the two matters can be made clearer by calling the first prime matter, to indicate that there is nothing prior to it (since it is prime, i.e., first) which is related to it as its matter, that of itself it has no substantial form, and that therefore it does not exist of itself; and by calling the second a subject, to indicate that there is something prior to it, namely prime matter, which is related to it as its matter, that it has a substantial form, and that it does indeed exist of itself.

This is why it is said that accidents, i.e., accidental forms, are in a subject (an ultimate existing subject); and why it is not said that substantial forms are in a subject.

Rather, substantial forms are in prime matter, which does not exist of itself, not being an ultimate existing subject, though it is an ultimate subject. Prime matter, having an incomplete existence, has existence from that which comes to it, i.e., from the substantial form. But the subject, having a complete existence, does not have existence from the accidental forms which come to it. Rather the accidental forms have existence from the subject. Though “matter” is most properly used to designate what is in potency to substantial existence, and “subject” to desginate what is in potency to accidental existence, sometimes one is used for the other, i.e., ”matter” for

“subject,” and vice versa.

Aquinas had said above both 1) that sperm and ovum are in potency to being a man, i.e., in potency to substantial existence; and 2) that the matter which is in potency to substantial existence is prime matter. Is one to

conclude, therefore, that sperm and ovum are the same as prime matter? — It seems that not; for prime matter of itself is absolutely formless, has no form of any sort;

whereas sperm and ovum, both, do indeed have a form. Besides, though prime matter is in potency to all substantial forms, it is in potency to them in a certain order.

Prime matter is in potency, first of all, to the lowest of the substantial forms, i.e., to the substantial forms of the elements, and through these to the substantial forms of mixed bodies, some of which become the food which is appropriate for human consumption. Human bodies produce sperm and ova out of some of this food, and the sperm and ova, in turn, via fertilization and gestation, become new human beings. In some way, the elements remain in mixed bodies, including human bodies. How they remain will be considered later on, at a more opportune point.

Form:

Substantial and Accidental

3. Sicut autem omne quod est in potentia potest dici materia, ita omne a quo aliquid habet esse, sive substantiale sive accidentale, potest dici forma; sicut homo, cum sit potentia albus, fit actu albus per albedinem, et sperma, cum sit potentia homo, fit actu homo per animam. Et quia forma facit esse in actu, ideo forma dicitur esse actus. Quod autem facit actu esse substantiale, dicitur forma substantialis, et quod facit actu esse accidentale, dicitur forma accidentalis.

Now just as everything which is in potency can be called matter, so too everything from which something has existence, whether substantial or accidental, can be called form. For example, man, being potentially white, becomes actually white because of whiteness; and sperm, being potentially man, becomes actually man because of the soul. Now, because form causes actual existence, form is said to be an act. What causes actual substantial existence is called a substantial form; and what causes actual accidental existence is called an accidental form.

Having talked about matter, i.e., about what is in potency, in 2., Aquinas turns in 3. to talk about form. Form is the actuality of the potentiality which is matter.

Whereas matter is that in a changing thing by which that thing can be what it is becoming; form is that, in a thing which has come to be, by which that thing is actually, now, what it was, before, only potentially (in its matter). The soul is that, in a human being which has come to be, by which the human being is a human being, i.e., by which the human being differs from the sperm and ovum out of which it came to be. To be sure, something of the sperm and ovum (i.e., prime matter, and certain elements, and certain accidental forms) survives and remains in some way in the human being which has come to be. And certain of these remaining ingredients, namely prime matter and the elements, together with the soul, constitute the essence of the human being which has come to be, and this essence differentiates that human being from nothingness. Not only does the human being differ from the sperm and ovum, the matter out of which it came to be, by reason of the human soul (this is the substantial form, the forma partis); but it differs from nothingness as well, by reason of its essence, i.e., by reason of the composition of what survives in it (from that out of which it came to be) and the human soul (this composite is the essence, the forma totius). Form differentiates. The substantial form, the forma partis, differentiates from matter. The essence, the forma totius, differentiates from nothingness.

Generation:

Substantial and Accidental

4. Et quia generatio est motus ad formam, duplici formae respondet duplex generatio: formae substantiali respondet generatio simpliciter; formae accidentali generatio secundum quid. Quando enim introducitur forma substantialis, dicitur aliquid fieri simpliciter, sicut dicimus: homo fit vel homo Page 8

generatur. Quando autem introducitur forma accidentalis, non dicitur aliquid fieri simpliciter, sed fieri hoc; sicut quando homo fit albus, non dicimus simpliciter hominem fieri vel generari, sed fieri vel generari album.

Because generation is a motion to form, there are two kinds of generation corresponding to the two kinds of form. There is generation simply, which corresponds to substantial form. And there is generation with respect to something or other, and this corresponds to accidental form. When a substantial form is introduced, something is said to come to be simply. We say, for example, that a man comes to be, or that a man is generated. But when an acccidental form is introduced, it is not said that something comes to be simply, but that it comes to be this. When a man comes to be white, for example, we do not say simply that the man comes to be, or that he is generated; but that he comes to be, or is generated as, white.

In 3., Aquinas had talked briefly about form, and about its two types, substantial and accidental. In 4., he turns to talk about generation, the way to form. And he begins by pointing out that generation is a certain sort of motion, or movement, which terminates in form. This implies, of course, that generation begins with, departs from, matter and privation. Generation is the passage, the change, from matter and privation to form. There are two kinds of generation, one with respect to each kind of form. There is 1) generation simply, the way to substantial form; in which case a thing comes to be as an ultimate existing subject, e.g., as a human being. There is 2) generation as something or other, the way to accidental form; in which case a thing, already an ultimate existing subject, becomes this or that, e.g., white or hot.

Corruption:

Substantial and Accidental

5. Et huic duplici generationi opponitur duplex corruptio, scilicet simpliciter et secundum quid. Generatio vero et corruptio simpliciter non sunt nisi in genere substantiae, sed generatio et corruptio secundum quid sunt in omnibus aliis generibus. Et quia generatio est quaedam mutatio de non esse ad esse, e converso autem corruptio de esse ad non esse, non ex quolibet non ente fit generatio, sed ex non ente quod est ens in potentia; sicut idolum ex cupro quod est idolum in potentia, non in actu.

There are two kinds of corruption opposed to these two kinds of generation. There is corruption simply, and there is corruption with respect to something or other. Now, generation and corruption simply are found only in the genus of substance, whereas generation and corruption with respect to something or other are found in all the other genera. And although generation is a kind of change from nonexistence to existence, and corruption conversely from existence to nonexistence, generation does not take place from just any kind of non being, but from the non being which is being in potency. A statue, for example, comes to be from bronze which is a statue in potency, not in act.

In 5., Aquinas notes that there are two kinds of corruption, corruption being opposed to generation, just as there are two kinds of generation. There is first corruption simply, which along with generation simply, occurs only in the genus of substance. There is secondly corruption with respect to something or other, which along with generation with respect to something or other, takes place in all the other genera. Not only is generation a motion to form; but, because of that, it is also a certain sort of passage or change from nonexistence to existence, inasmuch as form causes existence, as was pointed out above. The generation of a human being, for example, is the motion which terminates in the human soul, and it is because of the human soul that a human being begins, and continues, to exist. This motion begins in (departs from) nonbeing, but not from just any nonbeing; rather from that

nonbeing which is being in potency, i.e., from an appropriate matter with an appropriate privation. And the corruption of a human being is the opposite motion, the motion which terminates in the removal of the human soul, and through that in the discontinuance of existence for the human being. Whatever causes form, causes existence. Whatever removes form, removes existence.

Generation Requires Matter, Form and Privation

6. Ad hoc ergo quod sit generatio, tria requiruntur: scilicet ens potentia, quod est materia; et non esse actu, quod est privatio; et id per quod fit actu, scilicet forma. Sicut quando ex cupro fit idolum, cuprum quod est in potentia ad formam idoli, est materia; hoc autem quod est infiguratum sive indispositum, est privatio; figura autem a qua dicitur idolum, est forma; non autem substantialis, quia cuprum ante adventum illius formae habet esse in actu, et eius esse non dependet ab illa figura, sed est forma accidentalis. Omnes enim formae artificiales sunt accidentales. Ars enim non operatur nisi supra id quod iam constitutum est in esse a natura.

In order, therefore, that there be generation, three things are required: namely, being in potency, which is matter; nonbeing in act, which is privation; and that through which a thing comes to being in act, namely form. When, for example, a statue is made out of bronze, the bronze which is in potency to the form of the statue is the matter; the unshaped, or the unarranged, is the privation; and the shape from which the statue gets to be called a statue is the form. But this form is not a substantial form because the bronze, before the coming of that form, already has actual existence, and its existence does not depend on that shape. This form is, rather, an accidental form. All artificial forms are accidental forms.

For art works only on what has already been put into existence by nature.

In 6., Aquinas puts together, into a kind of brief summary, the requirements for generation. Three things are required, namely matter, form, and privation. Two of these, namely matter and privation, are required in that from which generation begins or departs, i.e., in the terminus a quo. The third, namely form, is required in the end result, or product, of the generation, i.e., in the terminus ad quem. Suppose that a statue is being made out of bronze. Before the change begins, the bronze is in potency to the shape of the statue (this is ens potentia, i.e., the matter); it is also without that shape (this is non esse actu, i.e., the privation). After the change, however, the bronze actually has the shape in virtue of which it both is, and is called, a statue (this is id per quod fit actu, i.e., the form). But this particular form, i.e., the shape of the bronze, Aquinas reminds the reader, is not a substantial form. And he gives two reasons: 1) the bronze is already in existence, as an ultimate existing subject, before it acquires that particular shape, and 2) that particular shape is the work of human hands, i.e., a product of human artistic activity. Human art works only on materials which have come into existence by the work of nature. Nothing can be manmade through and through. Human art presupposes nature; and God as well, one might add. What man creates, in his way, presupposes both what nature creates, in its way, and what God creates, in His.

The Meaning of “Nature” in the Title:

De Principiis Naturae

One might ask at this point: What exactly is this brief work of Aquinas about? That is, what exactly is the meaning of its title: De Principiis Naturae? What does

“principium” mean? But, more especially, what does “natura” mean? That is, what exactly is this natura of which these principles are the principles? — Aquinas makes clear in chapter three what “principium” means, by way of contrast with “causa” and “elementum,” and in terms of the distinction between intrinsic cause and Page 12

extrinsic cause. But, nowhere in this work does he give an account of what “natura” means.

The meaning of “principium” will be taken up in chapter three. But the meaning of “natura” will be taken up now, with help from what Aquinas writes elsewhere. In his commentary on the Metaphysics of Aristotle ( In V Metaph., lect. 5, nn. 808–823), Aquinas notes, following Aristotle, that “natura” has a number of related meanings.

First, it means the generation of generated things (generatio generatorum). The natura of a generated thing, its naturing so to say, is the process by which it is brought into existence. By a kind of extension from “natura” to “nativitas” and then to “nascentia,” Aquinas observes, “natura” is also used to mean, more specifically, the generation, or being born (nascentia), of living things (generatio viventium). Secondly, “natura” means that out of which a living thing comes to be as out of a primary intrinsic principle (… [id] ex quo illud quod nascitur, generatur primo, sicut ex intrinseco principio). It is not at all clear what this means, nor does Aquinas give an example to help remove the unclarity. Could this be a reference to the seed out of which living things come into existence? Isn’t an acorn, for example, that out of which an oak tree comes to be as out of a primary, i.e., initiating, principle; and one which remains in the oak tree, in some way, as the primary ingredient which directs its development? Thirdly, “natura” means, generally, the intrinsic principle of the motion, whether growth or alteration or local motion (or whatever), of any natural thing as such (as different from, and prior to, something artificial or manmade). Fourthly, “natura” means, more specifically, the matter out of which a natural thing comes to be, and which remains in it as an ingredient, matter being an intrinsic cause of motion. Fifthly, “natura” means, again more specifically, the form of a natural thing, i.e., the substantial form or forma partis, since the motion of natural things is caused more by their form than by their matter. Sixthly, “natura” means prime matter, or first matter, i.e., matter which has no matter of itself, whether absolutely first, as in the case of the matter of all ultimate existing Page 13

subjects which have come to be in substantial change; or with respect to some given genus of them, e.g., water might be said to be the first matter of all liquefiable natural things. Seventhly, “natura” means the essence of a natural thing, including both matter and form; and this is called the form of the whole, the forma totius.

The process of generation, generally, and that of being born, more specifically, continues Aquinas ( In V Metaph., lect. 5, nn. 824–826), got called natura before the substantial form did, since these processes are observable by sense, at least up to a point, whereas the form is not. Then the word “natura” was extended to substantial form, because these processes have a relation to it, i.e., they terminate in it. And since a substantial form is more real than a process, to have a natura came to mean primarily: to have a substantial form. Then matter was said to be a natura, inasmuch as it is receptive of substantial form. Then generation and being born were said to be, each of them, a natura, inasmuch as they are motions proceeding from, and terminating in, substantial form.

As regards the question posed just a bit above, namely: What exactly is this natura of which these principles (in the title: De Principiis Naturae) are the principles?, the following seems to be an acceptable answer, at least for the time being. Taking the opening sentence of 6., namely: “Ad hoc ergo quod sit generatio, tria requiruntur: scilicet … materia, … privatio, … [et] forma … ,” and putting it together with the opening sentence of chapter 2, namely: “Sunt igitur tria principia naturae, scilicet materia, forma, et privatio,” it seems not unreasonable to conclude that “natura” here means generatio, the process of coming to be. Moreover, matter, form and privation are explicitly identified as the principles of nature. From which one can conclude that, though both matter and form are natura, each in its own way; they are not what “natura” designates in the title, De Principiis Naturae. A thing cannot be its own principle, its own source, that out which it itself originates. De Principiis Generationis would seem to be a helpful rendering of De Principiis Naturae.

Nonetheless, one might ask, what is one to make out of the fact that, in some of its very early printed versions, the De Principiis Naturae gets the title De Principiis Rerum Naturalium? 2 Should one say that “natura” means res naturalis? Or, should one say that (though “natura” does not mean res naturalis) matter, form, and privation are the principles of a res naturalis as well as of generatio, i.e., of the process whereby a res naturalis comes to be? This second suggestion seems the more reasonable one. For, as a matter of fact, “natura” does not mean res naturalis. Secondly, matter and form are the intrinsic composing ingredients, or principles, indeed causes, of a res naturalis; and privation, though only an accompaniment of matter, and not an intrinsic composing ingredient of the res naturalis, is nonetheless a necessary principle of the res naturalis, though a per accidens one. And thirdly, as Pauson points out, variations in title, especially in the earlier manuscripts, seem “to indicate that originally there was no exact title, but each scribe affixed the title he thought suitable.”3

2 See Saint Thomas Aquinas, De Principiis Naturae, Introduction and Critical Text by John J. Pauson, Textus Philosophici Friburgenses, 2; Fribourg: Societe Philosophique, 1950;

p. 65, and pp. 36–39.

3 Pauson, op cit., p. 65.

Chapter Two—

Matter, Form and Privation

In chapter two, Aquinas talks about a number of things: about privation as a principle per accidens; about how privation differs from negation; about principles of coming to be and principles of being; about prime matter, both absolutely prime and relatively prime; about the ingenerability and the incorruptibility of matter and form; about the sort of numerical oneness which belongs to prime matter; about prime matter as of itself without form or privation, yet as in fact never without either.

His comments are aimed at making clear both 1) how matter, form and privation differ from one another, and 2) how they are related to one another — as principles of nature, i.e., of the process of natural (as different from artificial) generation.

Privation Is a Principle per accidens, but Necessary for Generation

7. Sunt igitur tria principia naturae, scilicet materia, forma et privatio; quorum alterum, scilicet forma, est id ad quod est generatio, alia duo sunt ex parte eius ex quo est generatio.

Unde materia et privatio sunt idem subiecto, sed differunt ratione. Illud enim idem quod est aes, est infiguratum ante adventum formae; sed ex alia ratione dicitur aes et ex alia infiguratum. Unde privatio dicitur principium non per se, sed per accidens, quia scilicet coincidit cum materia; sicut dicimus quod per accidens medicus aedificat. Medicus enim aedificat non ex eo quod est medicus, sed ex eo quod est aedificator, quod coincidit cum medico in uno subiecto. Sed duplex est accidens: scilicet necessarium quod non separatur a re, ut risibile ab homine; et non necessarium quod separatur, ut album ab homine. Unde licet privatio sit principum per accidens, non sequitur quod non sit necessaria ad generationem, quia materia a privatione numquam denudatur; inquantum enim est sub una forma, habet privationem alterius et e converso, sicut in igne est privatio aeris et in aere privatio ignis.

There are therefore three principles of nature, namely matter, form and privation. The second of these, namely form, is that toward which generation moves; the other two lie on the side of that from which generation departs. Whence, matter and privation are the same in subject, but they differ in description. The thing which is bronze is the very same thing which is unshaped, before the coming of the form. But it is said to be bronze for one reason, and unshaped for another. Whence, when privation is said to be a principle, it is not said to be a principle per se (i.e., because of itself), but per accidens (i.e., because of something other than itself), i.e., because it happens to be found together with matter. As when we say that it is per accidens that a medical doctor builds. For a medical doctor builds not because he is a medical doctor, but because he is a builder. Being a builder and being a medical doctor happen to be found together in the same subject. But there are two kinds of accident. There is, first, the necessary accident, which does not get separated from the thing of which it is an accident; for example, risible does not get separated from man. There is, secondly, the accident which is not necessary; and such an accident does get separated; for example, white from man. And so, though privation is a principle per accidens, it does not follow that it is not necessary for generation; because matter is never without privation. For insofar as it is under one form, it is with the privation of another, and conversely. For example, in fire, there is the privation of air, and in air the privation of fire.

Of the three principles of nature, begins Aquinas in 7., form is found in the terminus ad quem. Form is that toward which generation moves. The other two, i.e., matter and privation, on the other hand, are found in the terminus a quo. Matter and privation are that from which generation proceeds; and in such a way that, though they are the same in subject, they are different’ in description. That which can be (what it is becoming), and that which is not (what it is becoming), are one and the same thing. But that

which can be, and that which is not, are conceptually different (differunt ratione). The thing which is bronze, and the thing which is unshaped, are one and the same thing. But to be bronze and to be unshaped are quite different. The former is the matter, and the latter the privation.

Bronze is bronze, one ought to note, whether unshaped (as before the change, in the terminus a quo) or shaped (as after the change, in the terminus ad quem). And the shape of the shaped bronze is not, now, an ingredient of the nature of the bronze, just as the unshapedness of the unshaped bronze was not, then, an ingredient of the nature of the bronze. Bronze has its own form, as well as its own matter, by both of which it is both actually bronze and potentially a statue. And just as its own form is not an ingredient of the nature of its own matter, neither is its own matter an ingredient of the nature of its own form. Generally speaking, matter and form are ingredients of that which is composed out of them, and neither is an ingredient of the nature of the other. Moreover, the bronze is said to be in potency to the shape it now has ( in the terminus ad quem, after the change), just as it was said to be in potency to that shape when it did not yet have it (in the terminus a quo, before the change) — but in a different sense. In the terminus a quo, it was in potency as determinable or perfectible; in the terminus ad quem, it is in potency as determined or perfected. And this is so because after the change, as well as before the change, the shape is something over and above, something in addition to, the nature of the bronze; something which can perfect or can determine the bronze, the matter, in the terminus a quo; something which is determining or is perfecting the bronze, the matter, in the terminus ad quem.

Though privation is a principle of nature, Aquinas continues, privation is not a principle per se (i.e., because of itself), but rather per accidens (i.e., because of something else), namely because of the matter to which it attaches, or which it accompanies. Matter, in the terminus a quo, exists because of the form which it has.

And whatever the form which matter has, it has also some privation or other, the character of the privation being determined by Page 18

the character of the form. A thing is just what it is by reason of its matter and its form. Just what it is, and not what it is not (but is about to become). What it is, is real; both its matter and its form are real. What the thing is not (i.e., the privation), while the thing itself is still just what it is, in the terminus a quo, is not real. And this is why it is said that privation is not a principle per se. Privation does not exist of itself; it exists only because of the existing matter to which it attaches.

To clarify what he has been saying, Aquinas compares privation to the building activity of a medical doctor. It is not per se, i.e., not because he is a medical doctor, that the medical doctor builds. Rather, it is per accidens, i.e., because of something other than being a medical doctor. It is because the medical doctor is also a builder. One and the same thing — in this case, the same individual person — is both a medical doctor and a builder. Similarly, one and the same thing — in this case, the terminus a quo of the change — is both bronze (what can be a statue) and unshaped (what is not a statue). But, whereas it is not necessary that the medical doctor be a builder as well (each is a separable accident, or concomitant, of the other); it is necessary that matter have a privation (matter and privation are inseparable concomitants). What can be what it is about to become (matter), is not what it is about to become (privation), and necessarily. It cannot not be what it is about to become. Otherwise, it could not become that; for, it would already be that. What can receive a given form (matter) cannot now have that given form (privation). For example, in fire, which can be what it is about to become, namely air, there is, must be, the privation of air. And in air, which can be what it is about to become, namely fire, there is, must be, the privation of fire. If this were not so, then air could not become fire, because air would already be fire.

When Aquinas said above, “Sed duplex est accidens,” what exactly did he mean by the world “accidens”? His example of white in relation to man might suggest that he was talking about a predicamental accident, i..e, about that which exists in a substance as in an ultimate existing subject. For, white Page 19

is just such an accident. But he gave another example, namely risible in relation to man. And risibility is not a predicamental accident; it is rather a property of man, a property in the category of substance. Man is risible, because man is rational; and rational is the specific difference of man. Since white and risible, in relation to man, have this in common, namely that neither is of the conceptual content (ratio) of man; this suggests that “accidens” in the claim that “duplex est accidens” means: that which is found together with another without being of the conceptual content of that other. This suggestion fits the relation between matter and privation. They are found together, but neither is of the conceptual content of the other. Matter, the conceptual content of which is can be, is found together with privation, the conceptual content of which is is not. Furthermore, privation, like risibility, is a necessary accident; that is, just as risibility cannot be separated from man, neither can privation be separated from matter. For, what can be necessarily is not.

Privation, Not Negation

8. Et est sciendum quod, cum generatio sit ex non esse, non dicimus quod negatio sit principium, sed privatio, quia negatio non determinat sibi subiectum. Non videre enim potest dici etiam de non entibus, ut ‘chimaera non videt;’ et iterum de entibus quae non sunt nata habere visum, sicut de lapide. Sed privatio non dicitur nisi de determinato subiecto, in quo scilicet natus est fieri habitus, sicut caecitas non dicitur nisi de his quae sunt nata videre. Et quia generatio non fit ex non ente simpliciter, sed ex non ente quod est in aliquo subiecto, et non in quolibet, sed in determinato, — non enim ex quolibet non igne fit ignis, sed ex tali non igne, circa quem nata sit fieri forma ignis, — ideo dicitur quod privatio sit principium.

Although generation is from nonbeing, we do not say, it must be understood, that negation is a principle, but privation; because negation does not determine a subject for itself.

For the negation, “They do not see,” can be said even of things which do not exist. For example, “Chimeras do not see.” And again, even Page 20

of things which are not meant by nature to see, as of a stone. But a privation is not predicated except of a determined subject, namely of a subject which is meant by nature to come to have a certain capacity. For example, blindness is not predicated except of things which are meant by nature to see. And because generation does not take place from nonbeing simply, but from the nonbeing which is in some subject; and not in just any subject, but in a determined one — fire, for example, does not come to be from just any nonfire, but from the sort of nonfire in which the form of fire is meant by nature to come to be — this is why it is said that privation [not negation] is a principle.

In 8., Aquinas observes, and emphasizes, that though generation proceeds from nonbeing — which might lead one to think that negation is a principle of nature — it is privation, not negation, which is the principle. This is so, explains Aquinas, because negation does not pick out, or select, or designate a subject from which generation can appropriately depart. Negations can be predicated of anything at all, even of things which do not exist. For example, we can say, “Stones do not see”

or “Mountains do not see;” and even, “Nothingness does not see” or “Chimeras (monsters of my fantasizing mind) do not see.” But privations cannot be predicated except of things which, for some reason or other, do not have some capacity, or perfection, which they are meant by nature to have. For example, we can say, “This man is blind” or “This dog is blind;” but not, “Nothingness is blind” or “Stones are blind” or “Mountains are blind.” For men and dogs are meant by nature to have the capacity of sight; but nothingness and stones and mountains are not.

Moreover, generation is never from absolute nothingness; for that is creation. Generation is always from something which exists, and is of a given kind (the terminus a quo), to something else which exists, and is of another given kind (the terminus ad quem). The given kind of the terminus a quo is rooted in its form, and is the source of the potency (matter) and of the nonbeing (privation) which are required for that

particular sort of generation. The given kind of the terminus ad quem is rooted in the newly acquired form. Fire, exemplifies Aquinas, does not come to be from just any sort of nonfire, but from the sort of nonfire in which it makes sense to say there is a privation of the form of fire, i.e., the sort of nonfire which is meant by nature to receive the form of fire. Just as the privation designated by “is blind” requires an appropriate subject, for example a man or a dog; so too, the privation designated by “is not on fire” requires an appropriate subject, i.e., some combustible material, for example a piece of paper, but not a stone. Whereas paper can burn, can come to be “on fire,” a stone cannot. Similarly, whereas sperm and ovum can come to be a human being, a piece of paper cannot. ”Is not a human being,” as said of sperm and ovum (which are the terminus a quo of the generation of a human being), designates the privation which is appropriate for that generation. “Is not a human being,”

as said of a stone, designates only a negation. For a stone is not meant by nature to come to be a human being; the sperm and the ovum are. And this is why privation, concludes Aquinas, is one of the principles of nature, and negation is not.

Privation Is a Principle of Coming to Be, but Not of Being

9. Sed in hoc differt ab aliis, quia alia sunt principia et in esse et in fieri. Ad hoc enim quod fiat idolum, oportet quod sit aes, et quod ultimo sit figura idoli; et iterum quando iam idolum est, oportet haec duo esse. Sed privatio est principum in fieri et non in esse; quia dum fit idolum, oportet quod non sit idolum. Si enim esset, non fieret; quia quod fit non est, nisi in successivis, ut tempus et motus. Sed ex quo iam idolum est, non est ibi privatio idoli; quia affirmatio et negatio non sunt simul, similiter nec privatio et habitus. Item privatio est principium per accidens, ut supra expositum est; alia duo sunt principia per se.

Privation differs from the other principles in this: the others are principles both in being and in coming to be. For in order that a statue come to be, there must be the bronze [to begin with], and ultimately there must be the shape of the statue. And again,

when the statue is already in existence, these two [the bronze and the shape] must be there. But privation is a principle in coming to be and not in being; because while the statue is coming to be, it must be that the statue is not yet in existence. For, if it were in existence, it would not be coming to be; because what is coming to be does not yet exist, unless it is something successive, like time and motion. But, as soon as the statue is in existence, the privation of statue is no longer there, because affirmation and negation are not found together; neither are privation and the form of which it is the privation. Again, privation is a principle per accidens, as was explained above; the other two are principles per se.

In 9., Aquinas points out that though matter, form and privation — all three — are principles of coming to be, only matter and form are principles of being. To make his meaning clear, one must note that, when Aquinas points this out, his focus is on the nature, or essence, of the newly generated thing, the terminus ad quem. The matter which was in the terminus a quo before the change began — that matter survives in the terminus ad quem as an ingredient of what it is, i.e., as an intrinsic principle of its being. The form which the surviving matter receives, that too is an ingredient of the nature of the terminus ad quem, another intrinsic principle of its being. But the privation does not survive in the terminus ad quem as an ingredient of its nature; it does not survive at all. The privation is there only in the terminus a quo, and during the process of generation. But once that process is terminated, matter has received form (the form of which the privation had been the privation), and that particular privation is no longer there. Thus, that particular privation was there as a principle of the coming to be of the terminus ad quem, but is not there as a principle of the being of the terminus ad quem. To be sure, just as matter was there throughout the process of generation, so too was some form or other. Otherwise the matter could not have been in existence, nor therefore could any privation have been in existence. Matter cannot exist without form; and privation cannot exist without matter. And so, matter, form and privation — all three — are principles of the coming to be (fieri) of the terminus ad quem; but only Page 23

matter and form are principles of the being (esse) of the terminus ad quem. What is in process of coming to be, does not yet exist. This is why privation is there during the coming to be, but not beyond. And this is why privation (the privation, that is, which is a principle of nature) can be likened to successive realities, like time and motion, which, qua successive, both are (in one respect) and are not (in another respect). Privation is a nonbeing which is, as well as a being which is not — in a terminus a quo which is meant by nature (in a given appropriate process of generation) to receive the form of which the privation is a privation.

Matter and Privation

10. Ex dictis igitur patet quod materia differt a forma et a privatione secundum rationem. Materia enim est id in quo intelligitur forma et privatio; sicut in cupro intelligitur figura et infiguratum. Quandoque enim materia denominatur cum privatione, quandoque sine privatione; sicut aes, cum sit materia idoli, non importat privationem, quia ex hoc quod dico

‘aes,’ non intelligitur indispositum sive infiguratum. Sed farina, cum sit materia respectu panis, importat in se privationem formae panis, quia ex hoc quod dico ‘farina,’ significatur indispositio sive inordinatio opposita formae panis. Et quia in generatione materia sive subiectum permanet, privatio vero non, neque compositum ex materia et privatione, ideo materia quae non importat privationem, est permanens, quae autem importat, est transiens.

It is clear, therefore, from the things which have been said, that matter differs in description [definition] from form and from privation. For matter is that in which form and privation are understood; as, for example, the shape and the unshaped in bronze. Sometimes indeed matter is denominated as with a privation, sometimes as without a privation. Bronze, for example, as the matter of a statue, does not include a privation; because when I call it bronze, it is not understood to be unarranged or unshaped. But flour, as the matter of bread, does include in itself the privation of the form of bread, because when I call it flour, what is signified is the lack of arrangement, or the Page 24

disorder, which is opposed to the form of bread. And because in generation the matter, or subject, is there throughout, whereas the privation is not, and neither is the composite of matter and privation; the matter which does not include a privation is something permanent, whereas the matter which does, is something transient.

In 10., Aquinas reflects a bit more on the difference between matter and privation. He begins by noting that though matter differs from privation, it differs from form as well. And it differs from both of them in description, or definition (secundum rationem). Matter is that in which both form and privation can be found. Bronze, for example, is that in which both shape and lack of shape can be found. And sometimes matter is designated by a word which connotes the privation which is in it. For example, the word “flour” designates something which has the role of matter with respect to bread, and in such a way that “flour” connotes the privation of the form of bread. “Flour” means, whatever else it means: that which is not bread. “Flour” connotes the state of indisposition or disorder which is opposed to the form of bread.

But sometimes matter is designated by a word which does not connote the privation which is in it. The word “bronze,” for example, designates something which functions as matter with respect to a statue, but in such a way that its lack of shape is not connoted. Whatever “bronze” means, or does not mean, it does not mean: what is not a statue. Whereas “flour” says not yet bread, “bronze” does not say not yet statue. Still, just as “flour” says can be bread, so too “bronze” says can be a statue. And whereas the bronze survives in the statue as bronze, since “bronze” does not connote the privation which does not survive; flour does not survive in bread as flour, since “flour” does connote the privation which does not survive. The bronze is there throughout, as bronze (est permanens). The flour is not there throughout, as flour (est transiens). Matter and privation are radically different, since matter survives and privation does not. Similarly, matter and form are radically different, since matter survives and form does not. But, whereas to say that the privation does not survive is to say that it was Page 25

there (in the terminus a quo), then passed away (in the terminus ad quem); to say that the form does not survive is to say something quite different, namely that it was not there at all (in the terminus a quo), but came to be (in the terminus ad quem).

Prime Matter, Simply Prime and Relatively Prime

11. Sed est sciendum quod quaedam materia habet compositionem formae, sicut aes cum sit materia respectu idoli. Ipsum tamen aes est compositium ex materia et forma. Et ideo aes non dicitur materia prima, quia habet materiam. Illa autem materia quae intelligitur sine qualibet forma et privatione, sed subiecta est formae et privationi, dicitur materia prima propter hoc quod ante ipsam non est alia materia. Et hoc etiam dicitur ‘hyle.’ Et quia omnis definitio et omnis cognitio est per formam, ideo materia prima per se non potest cognosci vel definiri, sed per compositum, ut dicatur quod illud est materia prima, quod hoc modo se habet ad omnes formas et privationes sicut aes ad idolum et infiguratum. Et haec dicitur simpliciter prima. Potest etiam aliquid dici materia prima respectu alicuius generis, sicut aqua est materia prima in genere liquabilium. Non tamen est prima simpliciter, quia est composita ex materia et forma; unde habet materiam priorem.

Some matter, it must be understood, has in itself a composition with form, like bronze, when it is matter with respect to a statue. For, the bronze itself is something composed of matter and form. And so, bronze is not said to be prime matter, because it itself has matter. That matter, however, which is understood without any form and privation, but is subject to form and privation, is said to be prime matter, because of the fact that there is no other matter prior to it. And this is also called ‘hyle.’ And because every definition, and all knowledge, is through form, it follows that prime matter cannot be known or defined through itself, but through the composite, as when it is said that that is prime matter which is related to all forms and privations as bronze is to the statue and to the unshaped. And this matter is called Page 26

simply prime. But something can be called prime matter with respect to a given genus, as water is prime matter in the genus of watery things. But such matter is not simply prime, because it is itself composed of matter and form. And so, it has a prior matter.

In 11., Aquinas turns again to consider the nature of prime matter. Above in 2., he had pointed out a number of things about prime matter: prime matter is what is in potency to substantial existence; it is the matter out of which an ultimate existing subject in the natural world is made; it is not itself an ultimate existing subject, though it is an ultimate subject; of itself it has only an incomplete existence, which is completed and actualized by the substantial form which comes to it. Here in 11., Aquinas emphasizes two aspects of the nature of prime matter, namely 1) that it is not something composed of matter and form, and so there is no matter prior to it; and 2) that it is of itself unknowable and indefinable.

The first aspect. Prime matter is called prime, or first, precisely because there is nothing prior to it (it is first) which is related to it as its matter; precisely, in another way of saying it, because unlike natural substance, it is not composed of matter and form. If there were a matter prior to it, prime matter could not be prime. Prime matter of itself has no matter, and that is why of itself it can have neither a form nor a privation. Nonetheless, it is that in which, as in a subject, both form and privation are found.

But, there are matters other than prime matter. And, not being prime, these others are such that each of them is composed of matter and form, each of them has matter as an intrinsic ingredient. Bronze, for example, is matter with respect to a statue. But bronze itself is composed of matter and form. Bronze, therefore, is not prime matter, because it has a prior matter. Or, sperm and ovum are matter with respect to a human being; but both sperm and ovum, in turn, have a prior matter, a matter out of which each has come to be. Sperm and ovum, therefore, are not prime matter. There are

nonetheless matters which are prime matters in relation to a given genus of things, like water in relation to all watery things, or oil in relation to all oily things, or wood in relation to all wooden things. For whereas wood is an intrinsic ingredient of all wooden things, wood itself is not made out of wood. Wood which is prior to wood could not itself be wood. Nor could water which is prior to water be water. Nor oil, prior to oil, oil.

The second aspect. Prime matter, continues Aquinas, is such in itself that it is unknowable, indefinable, through itself. This is so because every definiton, indeed all knowledge, is through form, and form is not a component of the nature of prime matter. Form comes to prime matter, form exists in prime matter as in a subject; but form is not, not ever, an intrinsic ingredient of the nature of prime matter. Nonetheless, prime matter can be defined — or can be known, if one would rather not speak of defining prime matter — through the form which comes to it. It can be said that what prime matter is, is a potency for substantial form; or better, that prime matter is related to all substantial forms in the way in which bronze is related to all statueshapes. Better still, it can be said that prime matter is related to all substantial forms, and to all privations of substantial form as well, in the way in which bronze is related to all statueshapes (forms), and to the lack of these statueshapes as well (privations).

Prime matter has neither matter nor form nor privation. And although it is the subject in which form and privation are found, there is nothing which can be a subject in which it can be found. It cannot be known through itself since it has no form; nonetheless, it can be known through the form which is in it without being of it.

Why, someone might ask, did Aquinas say that, although prime matter cannot be known through itself, since it has no form as an intrinsic ingredient, it can be known through the composite (per compositum)? That is, why did he say “through the composite,” and not, “through form,” since he had just said that all knowledge is through form? His example, too,

seems to be a bit puzzling. For he says, “as when it is said that that is prime matter which is related to all forms and privations as bronze is to the statue and to the unshaped.” The unshaped to which bronze is related seems to coincide with the privations to which prime matter is related; but the statue to which bronze is related does not seem to coincide with the forms to which prime matter is related. The statue is a composite — a composite of bronze and the shape. But forms are not composites; a form is but one ingredient of the composite, the other ingredient being matter. And since matter is an ingredient of the composite, doesn’t saying that matter is knowable through the composite amount to saying that matter is in some way, at least in part, knowable through itself, precisely because it is a part (an ingredient) of the composite through which it is said to be knowable?

What is to be said? Perhaps this. When Aquinas says that prime matter can be known through the composite, he ought to be taken to mean: through that in the composite by which the composite is actual. And that, of course, is the substantial form. For a natural substance to be actual is for it to be different from the terminus a quo from which it was generated. And this difference is rooted in the substantial form. But, for a natural substance to be actual is also for it to be different from nonbeing. And this difference ie rooted in its essence, only part of which is the substantial form, the other part being matter. To be sure, the natural substance comes to differ from nonbeing (by its essence) only when it comes to differ (by its substantial form) from the terminus a quo from which it was generated. And it differs from that terminus a quo, it is to be emphasized, by its substantial form. And so, the substantial form is fundamentally that by which a natural substance, as well as the matter which is an intrinsic component of it, both is and is knowable.

Prime Matter and Substantial Form Are Ingenerable and Incorruptible

12. Et sciendum est quod materia prima, et etiam forma, non generatur neque corrumpitur, quia omnis generatio est ex aliquo ad aliquid. Illud autem ex quo est generatio, est materia; illud vero ad quod est, est forma. Si igitur materia vel forma generetur, materiae esset materia et formae forma in infinitum. Unde generatio non est nisi compositi, proprie loquendo.

It must be understood that prime matter, and form as well, is neither generated nor corrupted, because every generation is from something to something. Now that from which generation proceeds is matter, and that to which it proceeds is form. So that, if matter or form were generated, there would be a matter for matter and a form for form, endlessly.

Whence, there is generation only of the composite, properly speaking.

In 12., Aquinas continues reflecting on the nature of prime matter. Prime matter, he points out, is neither generable nor corruptible, because every generation is from something to something — from matter to form. Thus, if prime matter were generated, there would be a matter in it, out of which it came to be. There would, therefore, be a matter prior to prime matter, and so prime matter would not be prime. There would also be a form in it, by which prime matter would differ from that out of which it came to be. But, prime matter of itself is without any form. Similarly, if prime matter were corrupted, then again — since the generation of one thing is the corruption of another, both of which are composed of matter and form — prime matter would have in itself both a matter and a form. But, prime matter has neither. Lastly, if prime matter were generated or corrupted, there would be a matter for matter, and a form for matter, ad infinitum. And so, generation and corruption would be impossible.

Like prime matter, the substantial form too is both ingenerable and incorruptible. If it were generated or corrupted, then — since the generation of one thing is the corruption of another, both of which are composed of

matter and form — substantial form would have in intself both a matter and a form. But, substantial form has neither. Again, if substantial form were generated or corrupted, there would be a form for form, and a matter for form, ad infinitum. From which it would follow that there could be no ultimate existing subjects which come to be in change. Generation and corruption would be impossible.

The Numerical Oneness of Prime Matter

13. Sciendum est etiam quod materia prima dicitur una numero in omnibus. Sed unum numero dicitur duobus modis: scilicet quod habet unam formam determinatam in numero, sicut Socrates. Et hoc modo materia prima non dicitur una numero, cum in se non habeat aliquam formam. Dicitur etaim aliquid unum numero, quod est sine dispositionibus quae faciunt differe secundum numerum. Et hoc modo materia prima dicitur una numero, quia intelligitur sine omnibus dispositionibus a quibus est differentia in numero.

It should also be understood that prime matter is said to be one in number in all [natural] things. But, being one in number is said in two ways. First, that is said to be one in number which has a form which is determinately one in number, like Socrates. Prime matter is not said to be one in number in this way, since it has no form at all in itself. Secondly, a thing is said to be one in number if it is without the dispositions which cause things to differ in number. And prime matter is said to be one in number in this way, because it is understood to be without any of the dispositions from which difference in number arises.

In 13., Aquinas considers what it means to say that prime matter is one in number, or numerically one (one when it is counted), in all things. “All things,” of course, means: all things which have prime matter as an ingredient of their essences. To be numerically one means, primarily, to be countably one as a result of the division of matter — matter being divisible

only because of the quantity which it has, because of the substantial form which it has. But, only that which has a substantial form can be numerically one in this way, and prime matter has no substantial form. Or, only that which has matter can be numerically one in this way, and prime matter has no matter. Secondly, to be numerically one means to be such in itself that there is no way in which it can be divided so as to yield a numerical plurality, i.e., to be such, as Aquinas puts it here in 13., that it is without the dispositions which can bring about numerical difference. Prime matter of itself has neither matter nor substantial form nor quantity, and so is without any of the requirements for the possibility of numerical plurality.

And so, to be numerically one means: to be one among many of a same type; which many have resulted from a division, division presupposing divisibility, divisibility being based on quantity, quantity arising out of substantial form, and substantial form inhering in prime matter as in an ultimate subject. But, to be numerically one means also: to be one, but not among many of a same type; because there is no possibility of many of a same type. Prime matter is numerically one in this way.

To be numerically one means: there are others like it. Prime matter is not numerically one in this way. To be numerically one means also: there cannot be others like it.

Prime matter is numerically one in this way.

Though Prime Matter Exists, It Does Not Exist Through Itself

14. Et est sciendum quod, licet materia prima non habeat in sua ratione aliquam formam vel privationem, sicut in ratione aeris neque est figuratum neque infiguratum, tamen numquam denudatur a forma et privatione. Quandoque enim est sub una forma, quandoque sub alia. Sed per se numquam potest esse, quia — cum in ratione sua non habeat aliquam formam, non habet esse is actu, cum esse in actu non sit nisi a forma. Sed est solum in potentia. Et ideo quidquid est in actu, non potest dici materia prima.

Lastly, it should be understood that, although prime matter has in its nature neither any form nor any privation, just as bronze has in its nature neither to be shaped nor to be unshaped, it is nonetheless never without a form and a privation. For it is sometimes under one form, and sometimes under another. But through itself matter can never exist. Since it has no form as an ingredient of its nature, prime matter does not have actual existence, since actual existence is only from a form. Prime matter exists only in potency. And so, whatever has actual existence cannot be called prime matter.

In 14., Aquinas returns to a point he had made above, in 2., about the nature of prime matter, namely that it does not exist through itself. Neither form nor privation, notes Aquinas, are of the nature of prime matter, yet matter is never without some form and some appropriate privation. Sometimes prime matter has this form, sometimes that form; for example, sometimes the form of a dog, sometimes the form of a tree, depending on the nature of the agent cause(s) which have been exerting their causality. And so, prime matter cannot exist through itself, since it has no substantial form as an ingredient of what it is. Nonetheless, prime matter does exist —

through the form which happens to be in it without being of it, whether it is the form of a dog or of a tree or of whatever.

Thus, only that is real through itself, or exists through itself, which has a substantial form as an ingredient of what it is; and that is the substance, the ultimate existing subject, which has come to be. Whatever else is real, or exists, exists in some way through another. And that is how prime matter is real, or exists — through another, i.e., through the substantial form which is in it, but is not an ingredient of what it is. That, too, is how accidental forms exist, i.e., through another — through the substantial form of the substance of which they are the accidental forms.

To be real is to be different from nothingness. But real things differ from nothingness differently — some through themselves, some through another. Now, some things are substances, or ultimate existing subjects, and these differ from nothingness through themselves. Other things are either principles of a substance, or accidents of a substance, and these differ from nothingness through another, i.e., through the substance of which they are the principles or the accidents. Prime matter is not a substance; it is a principle of a substance. And so, prime matter is real through another, i.e., through substance, which is real through itself.

Although prime matter and the accidents have it in common that they are real through another, i.e., through substance; they differ in how they are related to the substantial form of the substance. Whereas prime matter is the subject in which the substantial form inheres, the substantial form is the subject (in some cases along with prime matter) in which the accidents inhere.

Chapter Three—

Agent and End; Principle, Cause and Element

In chapter three, Aquinas considers a number of things: the need of an agent for generation, in addition to matter, form and privation; the need of an end; the difference between a voluntary agent and a natural agent; what it means to intend an end; the four causes, namely material, efficient, formal and final; the difference between a principle and a cause; intrinsic causes and extrinsic causes; per se causes and per accidens causes; how an element differs from a principle and from a cause. His comments seem to be aimed primarily at 1) making clear that there are four kinds of cause, and 2) at making clear, in some detail, what an element is. Elements survive in the terminus ad quem of a change in a way which is both like, and quite unlike, the way in which prime matter survives. It is important, Aquinas seems to be saying, to note both the likeness and the difference.

In Addition to Matter and Form, There Must Be an Agent

15. Ex dictis igitur patet tria esse principia naturae, scilicet materia, forma et privatio. Sed haec non sunt sufficientia ad generationem. Quod enim est in potentia non potest se reducere ad actum; sicut cuprum quod est in potentia idolum, non facit se idolum, sed indiget operante, qui formam idoli extrahat de potentia in actum. Forma autem non potest se extrahere de potentia in actum. Et loquor de forma generati quam diximus esse terminum generationis. Forma enim non est nisi in facto esse; quod autem operatur est in fieri, idest dum res fit. Oportet igitur praeter materiam et formam esse aliquid principium quod agat, et hoc dicitur esse efficiens, vel movens, vel agens, vel unde est principium motus.

It is clear, therefore, from the things which have been said, that there are three principles of nature, namely matter, form and privation. But these are not sufficient for generation.

For what is in potency cannot bring itself into a state of actuality. Bronze, for example, which is a statue in potency, does not make itself be Page 35

a statue. It needs something actively working, which brings out the form of the statue from potency into act. Neither can the form bring itself out of potency into act; I am speaking of the form of the generated thing, the form which we have said is the endpoint of generation. For the form is not there until the thing has been made to be; and what is actually working is there during the coming to be, i.e., while the thing is being made. It is necessary, therefore, that there be in addition to the matter and the form some principle which does something; and this is said to be what makes, or moves, or acts, or that from which the motion begins.

In 15., Aquinas begins by noting that matter, form and privation — the three principles of nature — are not sufficient for generation. In generation, what is in potency is brought to a state of actuality; matter receives form. But, since actuality is not of the nature of potentiality, matter cannot receive form from itself. A piece of bronze, for example, cannot make itself be a statue; because the bronze, as bronze, is only in potency to the shape of the statue. There is need for an actively working cause, a sculptor in this case; a cause which has it in its active power to give the bronze the shape of a statue, thereby bringing what is in potency into a state of actuality.

Whereas the bronze is that out of which the statue is made, and not that which makes the statue; the sculptor is that which makes the statue, and not that out of which the statue is made.

Just as matter cannot bring itself to a state of actuality, neither can the form, continues Aquinas. Just as matter cannot be the operans, for one reason, i.e., because it is in potency; neither can the form, for another reason, i.e., because it does not yet exist. And he makes it very clear that he is talking about the form of the thing about to be generated, the form which is about to appear in the terminus ad quem — et loquor de forma generati quam diximus esse terminum generationis. The form of the generated thing is not there until after the thing has been generated. The operans — i.e., the thing which has it in its active power to give form to matter — must be

there before the thing is generated, i.e., during the process in which the thing comes to be, or while the thing which comes to be is being made.

And so, concludes Aquinas, in addition to the matter, by which something (the terminus ad quem) can be actual; and in addition to the form, by which something (the termiunus ad quem) will be actual; there is need for a third principle, something which acts — aliquod principiuim quod agat — a principle by the active power of which something (the terminus ad quem) is made to be actual. In addition to matter and form, there must be an agent.

In Addition to the Agent, There Must Be an End

16. Et quia, ut dicit Aristoteles in II Metaphysicae,4 omne quod agit non agit nisi intendendo aliquid, oportet esse aliud quartum, id scilicet quod intenditur ab operante, et hoc dicitur finis. Et est sciendum quod, licet omne agens tam naturale quam voluntarium intendat finem, non tamen sequitur quod omne agens cognoscat finem vel deliberet de fine.

Cognoscere enim finem est necessarium in his, quorum actiones non sunt determinatae, sed se habent ad opposita, sicut se habent agentia voluntaria; et ideo oportet quod cognoscant finem, per quem suas actiones determinent. Sed in agentibus naturalibus sunt actiones determinatae, unde non est necessarium eligere ea quae sunt ad finem. Et ponit exemplum Avicenna5 de citharaedo quem non oportet de qualibet percussione chordarum deliberate, cum percussiones sint deliberatae apud ipsum; alioquin esset 4 Aristotle, Metaph., Bk, II, ch. 2, 994 b 9–16. — Footnote references to authors cited by Aquinas will be of the briefest sort. For more extended footnotes, which include goodly portions of the text of the authors whom Aquinas cites, see Pauson, op. cit.

5 Liber Secundus Physicorum Avicennae, ” Sufficientia,” c. 10: Sicut qui scribit aut qui tangit cytharam; si incipiens discernere unamquamque litterarum aut unumquodque tonorum et voluerit scire numerum eorum, hebetabitur et impedietur et non procedet suo ordine in singulis quae incipit agere nisi in eo quod facit sine deliberatione. Quamvis initium illius operis et appetitus non fuerit nisi ex deliberatione; sed exercere illud primum in principio est sine deliberatione. (Ex. Cod. Paris. Nat. Lat. 6443, fol 22r–v). — From Basil M. Mattingly, O.S.B., De Principiis Naturae of St. Thomas Aquinas, Notre Dame, Indiana: University of Notre Dame, Doctoral Dissertation, 1957; p. (18).

inter percussiones mora, quod esset absonum. Magis autem videtur de agente voluntarie quod deliberet quam de agente naturali, et ita patet per locum a maiori, quod si agens voluntarie, de quo magis videtur, non deliberet aliquando, ergo nec agens naturale. Ergo possibile est agens naturale sine deliberatione intendere finem; et hoc intendere nihil aliud est quam habere naturalem inclinationem ad aliquid.

And because everything which acts, acts only by intending something, as Aristotle says in book two of the Metaphysics, there must be some fourth thing, namely that which is intended by that which is doing the work. This is said to be the end. And it should be understood that, although every agent, both natural and voluntary, intends an end, it does not follow nonetheless that every agent knows, or deliberates about, the end. To know the end is necessary in the case of those things whose actions are not determined, but are open to opposites, as are voluntary agents. And so, these things must know the end, through which they determine their actions. But in the case of natural agents, the actions are determined. Whence it is not necessary for them to choose the means to the end. And Avicenna offers the example of the one who sings while playing the cithara, who does not have to deliberate each time he strikes the strings, because he has deliberated about the strikings beforehand; otherwise there would be a delaying pause between strikings, which would be dissonant. Moreover, it seems more appropriate for a voluntarily acting agent to deliberate, than it does for a natural agent. And so, it seems clear by arguing a maiori, that if a voluntarily acting agent, for whom deliberation seems more appropriate, does not deliberate at least at times, neither therefore does a natural agent. It is possible, therefore, that a natural agent intend an end without deliberating about it. And this intending is nothing other than having a natural inclination toward something.

In 16., Saint Thomas reflects on the need for an end. Since everything which acts, he observes, acts only by intending something, there must be some fourth thing — in addition to these three: matter, form and agent — which moves the agent. Matter cannot give itself a form. The form cannot bring itself into existence. It is the agent which gives form to matter. But, if

the agent were not inclined, either by its own choice or by its own nature, to do some work, to perform some activity; no work would be done, no activity would be performed. And so, no form would be given to matter. And this is why, as Aquinas notes elsewhere, the end is said to be the cause of causes, i.e., the cause of the causality of the causes. The end causes the agent to function as an agent, i.e., to give form to matter, thereby causing the form and the matter to function, respectively, as form and matter.

But, there is a difference, observes Aquinas, between a voluntary agent and a natural agent. A voluntary agent knows, and deliberates about, the end; knows, and deliberates about, the various means to the end; then freely selects an end, thereupon freely choosing the means thereto. A natural agent, on the other hand, is not open to considering pursuing different means to previously selected ends. A natural agent neither selects its ends, nor chooses the means thereto. The actions of a natural agent are set or determined by its nature, just as, and because, the ends which it pursues are determined by that same nature.

Thus, both voluntary agents and natural agents act for an end. And both intend the end. But this — that both intend the end — does not mean, points out Aquinas, that both know and deliberate about the end and about the means thereto. For, whereas the actions of a voluntary agent are not determined by its nature, those of a natural agent are. And so, it is necessary for the voluntary agent to know and to deliberate, but not for the natural agent. To say that a natural agent intends a given end is to say simply that it is inclined by its nature to perform the activities by which it achieves that end. Avicenna, points out Aquinas, proposes the example of the person who sings while playing the cithara. This person, though a voluntary agent, does not have to stop to think and deliberate each time he strikes the strings, because he has thought out and planned and practiced the strikings many times beforehand, so much so, that his playing has become a habit, a kind of second nature. Thus, by an argument a maiori, since a voluntary agent —

for whom deliberation seems more appropriate than for other sorts of agents — does not, at least at times, have to deliberate about ends and the means thereto —

neither should a natural agent have to. And so, concludes Aquinas, it is possible for a natural agent to intend an end without deliberating either about that end or about the means thereto. To say that a natural agent intends an end is simply to say that it has a natural inclination to perform the activities by which that end can be achieved.

Four Causes, Three Principles

17. Ex dictis igitur patet quod sunt quatuor causae, scilicet materialis, efficiens, formalis et finalis. Licet autem principium et causa dicantur quasi convertibiliter, ut dicitur in V

Metaphysicae,6 tamen Aristoteles in libro Physicorum 7 ponit quatuor causas et tria principia. Causas autem accipit tam pro extrinsecis quam pro intrinsecis. Materia et forma dicuntur intrinsecae rei, eo quod sunt partes constituentes rem; efficiens et finalis dicuntur extrinsecae, quia sunt extra rem. Sed principia accipit solum causas intrinsecas. Privatio autem non nominatur inter causas, quia est principum per accidens, ut dictum est. Et cum dicimus quatuor causas, intelligimus de causis per se, ad quas tamen causae per accidens reducuntur, quia omne quod est per accidens, reducitur ad id quod est per se.

It is clear, therefore, from the things which have been said, that there are four causes, namely material, efficient, formal and final. And although “principle” and “cause” are used as though they were convertible, as is said in book five of the Metaphysics, nonetheless Aristotle in his book the Physics writes that there are four causes and three principles. He takes the causes to be both extrinsic and intrinsic. Matter and form are said to be intrinsic to a thing, because they are parts constituting the thing. The efficient and the final are said to be extrinsic, because they are outside the thing. But, as principles he takes only the intrinsic causes. And privation is not named among the causes, because it is a principle per accidens, as has been said.

6 Aristotle, Metaph. , Bk. V, ch. 1, 1013 a 16–17.

7 Aristotle, Physics, Bk. I, ch. 6, 189 b 16–18; ch. 7, 191 a 20–21; Bk. II, ch. 3, 195 a 15.

And when we say there are four causes, we understand this to refer to the per se causes, to which the per accidens causes are reduced, because everything which is per accidens is reduced to that which is per se.

In 17., Aquinas makes it his concern to begin to clarify the difference between cause and principle. He continues this clarifying concern in 18. .

“Principle” and “cause” are used in different ways. Sometimes they are used convertibly, notes Aquinas, so that whatever is called a principle is called a cause, and whatever is called a cause is called a principle. When used convertibly, it is obvious that both “principle” and ”cause” mean what “cause” means, i.e., that from which the existence of something else follows. For example, the sculptor and the bronze are “principles,” or “causes,” of the statue in this sense; for both contribute something to the existence of the statue. This seems to be the point of the reference to book five of the Metaphysics, where Aristotle notes that “principle” and

“cause” are used “quasi convertibiliter,” as Aquinas puts it, i.e., as though they were convertible.

But, sometimes “principle” and “cause” are not used convertibly. And when this happens, whatever is said to be a cause is said to be a principle, but not vice versa.

For there are, in this usage, principles which are not causes; for example, unshaped in the change from bronze to statue. Unshaped is a principle of this change, meaning that it counts as something from which the change begins, “principle” (from the Latin ” principium“) meaning simply a beginning point; but not a beginning point from which the existence of something else follows. The existence of the statue does not follow from the unshaped; though it does follow from the bronze and the sculptor and the shape and the intended end. And these, of course, are causes. The unshaped contributes nothing to the existence of the statue.

Moreover, continues Aquinas, sometimes “cause” is used to refer to both the intrinsic causes (matter and form) and the extrinsic causes (agent and end), “intrinsic”

naming those causes which are ingredients of the nature of the effect, and “extrinsic” naming those which are not ingredients of the nature of the effect. The bronze and the shape, for example, are ingredients of the nature of the effect, i.e., of the statue, whereas the sculptor and his intended end are not. By way of difference,

“principle” is sometimes used to refer to the intrinsic causes only, e.g., to the bronze and to the form. Thus, matter and form are both principles and causes, because both are intrinsic causes. But, privation is not listed among the causes, because it is a per accidens principle, i.e., a principle which attaches to, or accompanies, matter, which is a per se principle, a principle through itself, as explained above. And so, when it is said that there are four causes, the reference is to per se causes.

Privation, thus, is not counted among the causes, because it is of itself neither a cause, nor a principle (and what is not a principle cannot be a cause). This seems to be the point of the reference to the Physics of Aristotle, where Aristotle notes that there are four causes, but three principles.

Aquinas concludes 17. with the observation that per accidens causes are reduced to per se causes, “because everything which is per accidens is reduced to that which is per se.” What exactly does this mean?, one might ask. That is, what does “reduced” mean in the claim that “everything which is per accidens is reduced to that which is per se“? And what exactly is the point of observing that per accidens causes are reduced to per se causes?

The Meaning of “Reduced”

“Reduced” means literally: brought back to, or led back to. To what? To something (the per se) without which it could not be, or could not be understood. The per accidens is whatever it is (or is said to be) — whether a cause, or a principle, or something real — through, or because of, something other than itself, simply because it cannot be whatever it is (or is said to be)

through, or because of, itself, since it lacks something, or is somehow deficient or incomplete. An accident, like quantity or quality or relation, for example, is something real per accidens, i.e., through, or because of, something other than itself, namely because of the substance of which it is an accident. An accident cannot be real because of itself, simply because it is an accident; as an accident, it lacks something, is deficient, is incomplete. It is such of itself that it is real only because of something other than itself, because of that in which it inheres, namely substance. And substance is such of itself that it is real because of itself. Of itself, a substance is an ultimate existing subject. — Similarly, privation is a principle (and a cause) per accidens, i.e., because of the matter to which it attaches, which it accompanies, in which it is found. And matter is a principle per se. Privation is lacking, is deficient, is incomplete, in a way in which matter is not; though matter itself is lacking, deficient, incomplete, in a way in which a substance is not. Matter, along with form, is an ingredient of the essence of a substance, whereas privation is not. Matter has something in it (an essence of sorts) whereby it differs from nothingness, though it cannot assert this difference unless it has a form. Privation has nothing in it whereby it differs from nothingness; so that, even though privation is found only in a matter which has a form, it cannot, even so, assert itself as different from nothingness. Whereas matter has an essence of sorts, privation has no essence of any sort at all.

Similarly, again, the medical doctor who builds a house is a per accidens efficient cause of the house. For he builds the house not because he is a medical doctor, but because he is also a builder. Being a medical doctor is something which attaches to, accompanies, is found together with, being a builder. Again, the man who marries a virtuous and beautiful woman, who is also wealthy beyond measure, can be said to be motivated per accidens by her wealth, per se by her virtue and her beauty.

He marries her not because she is wealthy, but because she is virtuous and beautiful; just as the medical doctor builds a house not because he is a medical doctor, but because he is a builder.

Accidents are real per accidens, i.e., because of substance. Privations are principles (and causes) per accidens, i.e., because of matter. The medical doctor builds per accidens, i.e., because of being a builder. The man marries the wealthy woman per accidens, i.e., because of her virtue and beauty. Substance is real per se, i.e., because it is an ultimate existing subject. Matter is a principle (and a cause) per se, i.e., because it is matter. The builder builds per se, i.e., because he is a builder.

The virtuous and beautiful woman is the motivating (final) cause per se, i.e., because she is virtuous and beautiful.

The Point of Observing That per accidens Causes Are Reduced to per se Causes The point, now, of the observation that per accidens causes are reduced to per se causes should be clear. It is simply this. If there were no per se causes, there could be no per accidens causes either. Indeed, there would be no causes at all. Similarly, with respect to principles. And absolutely universally, if there were nothing whatever which is per se — whether a cause, or a principle, or something real, or an item of knowledge — there would be absolutely nothing at all.

Principle and Cause Defined

18. Sed licet principia ponat Aristoteles pro causis intrinsecis in I Physicorum, 8tamen, ut dicitur in XI Metaphysicae, 9 principium proprie dicitur de causis extrinsecis, elementum de 8 The reference is to what Aristotle does in the whole of Bk. I of the Physics, but in particular to his own account of the intrinsic principles in ch. 7, and to his response to the difficulties of earlier thinkers in ch. 8.

9 Aristotle, Metaph., Bk, XII, ch. 4, 1070 b 22–27. This point is not very clear in Aristotle, notes Mattingly ( op. cit. , p. (20), footnote 2). Aristotle says: Since not only the elements present in a thing are causes, but also something external, i.e., the moving cause, clearly while ‘principle’ and ‘element’ are different, both are causes, and ‘principle’ is divided into these two kinds [intrinsic and extrinsic?] … But Aquinas comes to a clarifying rescue: … nam principium proprie dicitur quod est extra sicut movens … Elementum proprie dicitur causa intrinseca ex qua constituitur res … ( In XI Metaph., lect. 4, nn. 2468–2469).

causis quae sunt partes rei, idest de causis intrinsecis. Causa autem dicitur de utrisque, licet quandoque unum ponatur pro altero; omnis enim causa potest dici principium et omne principium causa. Sed tamen causa videtur addere supra principium communiter dictum, quia id quod est primum, sive ex eo consequatur esse posterioris sive non, potest dici principium, sicut faber dicitur principium cultelli, quia ex eius operatione est esse cultelli; sed quando aliquid movetur de nigredine ad albedinem, dicitur quod nigredo est principium illius motus, et universaliter omne id a quo incipit esse motus dicitur principium, tamen nigredo non est id ex quo consequitur esse albedinis. Sed causa dicitur solum de illo primo, ex quo consequitur esse posterioris. Unde dicitur quod causa est id ex cuius esse sequitur aliud. Et ideo illud primum a quo incipit esse motus non potest dici causa per se, etsi dicatur principium. Et propter hoc, privatio ponitur inter principia et non inter causas, quia privatio est id a quo incipit generatio. Sed potest etiam dici causa per accidens, inquantum coincidit cum materia, ut supra expositum est.

But, although Aristotle uses “principles” to refer to intrinsic causes in book one of the Physics; nonetheless, as is said in book eleven of the Metaphysics, “principle” is said properly of extrinsic causes, and ”element” of causes which are parts of a thing, i.e., of intrinsic causes. “Cause,” moreover is said of both; even though one is sometimes used for the other, for every cause can be called a principle, and every principle a cause. Still, however, cause seems to add something to principle taken commonly, because that which is first, whether the existence of a posterior follows from it or not, can be said to be a principle. For example, the maker is called a principle of the knife, because the existence of the knife comes from his work. But when something is changed from black to white, black is said to be a principle of that change; and universally everything from which a change begins is said to be a principle. Black, however, is not something from which the existence of white follows. “Cause” is said of something which is first only if the existence of a posterior follows from it. Whence it is said that a cause is that from the existence of which another follows. And so, something first from which a change begins cannot be called a Page 45

cause just because it is something first, even though it is called a principle. And this is why privation is placed among the principles and not among the causes, because privation is that from which generation begins. But it can also be called a cause per accidens, inasmuch as it is an accompaniment of matter, as was explained above.

In 18., continuing the concern of 17., Aquinas makes clear exactly how cause differs from principle. He points out what the two have in common. He also gives a definition of each.

“Principle,” begins Aquinas, can be used to refer to intrinsic causes only (to matter and form), as Aristotle does in book one of the Physics, where he uses “principle”

to refer, as well, to privation, which accompanies matter as a kind of intrinsic attachment. For he speaks there of three principles of nature — matter and form ( per se principles), and privation (a per accidens principle).

But “principle”can be used, and properly, to refer to extrinsic causes as well (to agent and end), as Aristotle notes in book eleven of the Metaphysics. Moreover,

“element” can be used, though not properly, to refer to any sort of intrinsic cause. When used properly, however, “element” refers to intrinsic causes of a special sort, i.e., of the sort which are the material parts of some whole, but are themselves made up of a matter and a form. And “cause” can be used to refer to both, i.e., to the extrinsic as well as to the intrinsic. Still, ”cause” and “principle” are used at times for one another, as has been said. Nonetheless, there is a sense of “cause” in which it adds to the meaning of “principle.” “Principle,” taken commonly, means something first (a primum) from which something else, a posterior, begins or takes its origin, whether the existence of the posterior follows from it or not (this is a definition of principle which can be predicated of a cause). But “principle,”

taken less commonly, and “cause” have this in common: each is something first (a primum), from which something else, a posterior, begins, or takes its origin. If the existence of the posterior follows from the primum, i.e., if the primum contributes something to the existence of the posterior; the primum is a principle which is also a cause (this is the definition of cause). Matter, form, agent and end are principles which are also causes. If, on the other hand, the existence of the posterior does not follow from the primum, the primum is simply a principle, without being also a cause (this, too, is a definition of principle, but a definition which cannot be predicated of a cause). In the change, for example, in which something black becomes white, the primum black is a principle, but without being a cause. Black is neither the matter, nor the form, nor the agent, nor the end of the effect, i.e., of the white thing. So, too, privation is a principle which is a principle only. Privation contributes nothing to the existence of the effect. What contributes to the existence of the effect is either a part of the essence of the effect, i.e., either its matter or its form; or something which is productive of the essence of the effect, i.e., the agent which by its activity gives form to matter (thereby constituting the essence), because it has been motivated by some end. Essence is that, intrinsic to a thing, whereby the thing has existence. Privation is neither a part of essence; nor an agent or a motivating end, which are productive of essence. And this is why privation, concludes Aquinas, is placed among the principles, for privation is, indeed, something from which generation takes its origin; but not among the causes, for it contributes nothing to the existence of the effect. Nonetheless, a privation can, without harm and without risk to truth, be called a cause, so long as it is called a cause per accidens, i.e., because of the matter to which it attaches, or in which it inheres, matter being a cause per se. Every per accidens is the per accidens which it is only because of the appropriate per se to which it is related, on which it depends, without which it would not be anything at all.

Element Defined

19. Elementum autem non dicitur proprie nisi de causis ex quibus est compositio rei, quae proprie sunt materiales. Et iterum non de qualibet causa materiali, sed de illa ex qua est prima compositio; sicut non dicimus quod membra sunt elementa hominis, quia membra etiam componuntur ex aliis. Sed dicimus quod terra et aqua sunt elementa, quia haec non componuntur ex aliis corporibus; sed ex ipsis est prima compositio corporum naturalium. Unde Aristoteles in V Metaphysicae 10 dicit quod “elementum est id ex quo componitur res primo, et est in ea, et non dividitur secundum formam.” Expositio primae particulae, scilicet “ex quo componitur res primo,” patet per ea quae diximus. Secunda particula, scilicet

“et est in ea,” ponitur ad differentaim illius materiae quae ex toto corrumpitur per generationem; sicut panis est materia sanguinis, sed non generatur sanguis nisi corrumpatur panis; unde panis non remanet in sanguine, et ideo non potest dici panis elementum sanguinis. Sed elementa oportet aliquomodo remanere, cum non omnino corrumpantur, ut dicitur in libro De Generatione. 11 Tertia particula, scilicet “et non dividitur secundum formam,” ponitur ad differentiam eorum quae habent partes diversas in forma, idest in specie;

sicut manus cuius partes sunt caro et ossa, quae differunt secundum speciem. Sed elementum non dividitur in partes diversas secundum speciem, sicut aqua, cuius quaelibet pars est aqua. Non enim oportet ad esse elementi ut non dividatur secundum quantitatem, sed sufficit si non dividatur secundum speciem; et si etiam nullo modo dividatur, dicitur elementum, sicut litterae dicuntur elementa dictionum.

Element is said properly only of those causes out of which the composition of a thing arises, and which are properly material. And not of just any material causes, but of those out of which the thing’s primary composition arises. We do not say, for example, that his bodily members are the elements of a man, because the members themselves are composed of other things. But we do say that earth and water are elements, because these are not composed of other bodies. Rather, it is out of them that 10 Aristotle, Metaph., Bk. V, ch. 3, 1014 a 26–27.

11 Aristotle, De Gen. et Corrupt., Bk. I, ch. 10, 327 b 29–31.

the primary composition of natural bodies arises. Whence Aristotle says in book five of the Metaphysics that “an element is that out of which a thing is primarily composed, which is immanent in the thing, and which is indivisible according to form.” The explanation of the first part, namely “out of which a thing is primarily composed,” is clear from the things we have said. The second part, namely “which is immanent in the thing,” is used to differentiate an element from the sort of matter which is totally corrupted by generation. Bread, for example, is the matter of blood, but blood is not generated unless the bread is corrupted. Whence bread does not remain in blood, and so bread cannot be said to be an element of blood. Elements must remain in some way, since they are not entirely corrupted, as is said in the book On Generation. The third part, namely “and which is indivisible according to form,” is used to differentiate an element from those material parts which have parts which are diverse in form, i.e., in species. From the hand, for example, whose parts are flesh and bones, which differ according to species. But an element is indivisible into parts which are diverse according to species; like water, each part of which is water. And it is not necessary for an element that it be indivisible according to quantity; it suffices that it be indivisible according to species. And even if it is in no way divisible, it is said to be an element, as letters are said to be the elements of speech.

Having defined principle and cause in 18., Aquinas turns in 19. to make clear what an element is. An element is a special kind of principle. It is a principle which is also a cause — but a material cause, and of a special kind.

Elements, begins Aquinas, are material causes out of which a natural body comes into existence. But an element is not just any kind of material cause (component, or ingredient). Elements are material ingredients of a primary sort. That is, whereas other natural bodies are composed out of them, there Page 49

are no material ingredients, no natural bodies, prior to them, out of which they are composed. An element, like any principle, is a primum. It has been said that the elements have no elements of their own. Arms and legs, and the like, exemplifies Aquinas, are not the elements of a man, because they are, in turn, composed out of other bodies, like flesh and bones. Water and earth, however, continues Aquinas, are elements; for there are no prior bodily things out of which they are composed.

Today, of course, we know that water and earth are composed out of prior bodily ingredients, and so cannot be elements. Water, for example, is composed out of hydrogen and oxygen. Hydrogen and oxygen, too, are made out of prior constituents, e.g., protons and electrons; and protons, too, out of prior constituents still —

quarks. Are quarks, then, among the elements of all natural bodies? Whether or not quarks are elements of natural bodies is something to be decided by the empirical methods of contemporary physics. This much is clear, nonetheless, about what an element is: it is a material ingredient of a bodily sort which has no such bodily ingredients of its own. It is a bodily ingredient which is a primum.

But there is more to what an element is, continues Aquinas, and this more is what Aristotle has in mind when he writes, in book five of the Metaphysics, that “an element is that out of which a thing is primarily composed, which is immanent in it, and which is indivisible according to form.” The first part of this account of what an element is, of this definition of element, namely “out of which a thing is primarily composed,” expresses the two points noted in the preceding paragraph: 1) the words

“out of which” are used to indicate that an element is a material ingredient of a bodily sort; and 2) the word “primarily” is used to point out that the element itself has no prior bodily ingredients out of which it is constituted.

The second part, namely “which is immanent in the thing,” expresses how an element differs from any and every principle which is of a passing or transient sort, whatever it may be, whether a privation, or a contrary, or a completely corrupted matter, or matter taken with a privation or with a contrary. These are, all of them, passing or transient, rather than remaining. An element must remain in some way in that of which it is an element. For example, in the change in which a green apple becomes a red apple, the privation, nonred, does not remain in the red apple. Neither does the contrary, green. Neither does the matter taken with the contrary, green apple, remain. Lastly, neither does the matter taken with the privation, nonred apple, remain. And in the change in which bread becomes blood, the bread does not remain as bread. For, when bread becomes blood, bread is completely corrupted, and so does not remain. Bread, therefore, cannot be an element of blood. Earth, water, air and fire — in the proportion and arrangement appropriate to a red apple, or to blood — would remain, according to Aquinas. According to what we know today, however, we would say perhaps that what remains are certain sorts of quarks, and certain sorts of leptons, in the arrangement and proportion required for being a red apple, or for being blood.

The third part, namely “and which is indivisible according to form,” expresses how an element differs from those material parts which have parts which differ in kind;

for example, to express how an element differs from a hand. A hand is a material part of a man, and the hand itself has material parts, e.g., flesh and bones. But flesh is a part of one kind, and bone is a part of another kind. Flesh and bones differ in kind from one another, as well as from the hand, the whole, of which they are parts.

Taking water as an element, as Aquinas would, one could note that water is indeed divisible into parts; but each part of water is just water. The parts into which water is divisible are, all of them, the same in kind with one another, and with the whole of which they are the parts. Similarly, the parts into which air is divisible are, each of them, just air. Each part of air, like every other part of

air, and like the whole of which each is a part, is just air. Is it the case — if a quark is divisible — that each of its parts, is just a quark? And, if a lepton is divisible, is each of its parts just a lepton?

But further, as Aquinas explains in his commentary on book five of the Metaphysics, this last part of the definition of element expresses how an element differs from prime matter, too, which has no form or species at all. An element has a form or species. It is, after all, a natural body. And it is indivisible into species which are diverse from its own. Prime matter cannot be an element, simply because it is not a natural body; and so, unlike an element, it cannot have a species with respect to which it is indivisible. It is clear, from the immediately preceding, that although an element, unlike other natural bodies, cannot itself be composed out of prior natural bodies; it is nonetheless something composed — composed out of prime matter and substantial form. All natural bodies are composed out of prime matter and substantial form.

Lastly, adds Aquinas, it is not necessary for an element that it be indivisible into quantitative parts. Earth, water, air and fire, as Aquinas sees it, are elements — yet they are divisible into quantitative parts (each of which, of course, is the same in kind as the element which was divided). What is required for an element is that it be indivisible into quantitative parts which differ in kind. (Of course, if something is indivisible into quantitative parts, it must be indivisible into quantitative parts which differ from one another in kind, or species, as well. And so, such a thing could be an element, if there could be such a thing; and if such a thing could really be a material ingredient of a bodily thing.) Letters, i.e., spoken letters, notes Aquinas, are in a way like earth, water, air and fire, i.e., they are elements, yet they are divisible into quantitative parts — but of a temporal sort. To explain. Speech — i.e., language sounds (dictiones) — ranges from the complex to the simpler to the simplest. A sermon, for example, is a complex dictio, which is made up of paragraphs (simpler), which are made up of sentences (simpler), which are made up of words (simpler), which are made up of syllables

(simpler), which are made up of letters which are either consonants or vowels (the simplest). As the simplest, neither consonants nor vowels are made up of prior language sounds. There are no prior language sounds. And so, spoken letters, i.e., consonants and vowels, are the elements of speech. They cannot be divided into quantitative parts which differ in kind from one another, and from the consonants and vowels themselves. When divided, they are divided into parts each of which is the same in kind as all the others, and as the whole which was divided. That is, when a vowel sound is divided, each of its parts is a vowel sound — temporally shorter, but a vowel sound nonetheless. And when a consonant sound is divided, each of its parts is a consonant sound — temporally shorter, but a consonant sound nonetheless. It is to be emphasized that this is a division with respect to time; and that each of these parts is a temporal part, each becoming temporally shorter as the division proceeds. And this is why Aquinas observes, at the end of 19., that letters (sounded or spoken) are elements which are in no way divisible, i.e., not only with respect to species, but with respect to quantity as well. For, spoken or sounded letters are not three dimensional.

At this point, one might raise the question: Are there natural bodies which are indivisible into quantitative parts, and so indivisible into quantitative parts which differ in kind? A molecule of water, we know today, is divisible, resolvable, into hydrogen and oxygen; and hydrogen and oxygen into protons, neutrons, and electrons; and protons and neutrons, in turn, into quarks. Are quarks indivisible into quantitative parts, and so incapable of division into quantitative parts which differ in kind? (What does it mean to say, as physicists at times say today, that a quark is dimensionless?) Or, are quarks divisible into quantitative parts? And if so, do these parts differ in kind from one another, and from the divided quark itself? Or, are they the same in kind with one another, and with the divided quark itself? Does physics have an answer to these questions? They are certainly not questions which philosophy can answer.

In his commentary on the Metaphysics, Aquinas adds an interesting and helpful clarification as regards how indivisibility according to species is to be understood.

When it is said that an element is indivisible into parts which are diverse according to species, both from one another and from the whole which has been divided; this is not to be understood of parts which result from a simple quantitative division, but of parts which result from a division because of alteration. Each quantitative part of a piece of wood is just wood, yet wood is not an element. One simply takes a saw, or a knife, and cuts the wood up into quantitative parts. This is a simple quantitative division. But hydrogen and oxygen are, neither of them, water. Nor can one simply take a knife to water, and cut it up into hydrogen and oxygen.

Hydrogen and oxygen are indeed parts of water (quantitative parts); but they come into being from water because of a decomposing alteration. There is a way to decompose water, to alter water, so as to retrieve the hydrogen and oxygen out of which it came to be. But the way is not a simple quantitative division. One does not cut it up with a knife. One alters the water by using the agent causality of sulfuric acid and electricity.

Similarly, the two uquarks and the one dquark which compose a proton are not themselves protons. Nor can one simply take a knife to a proton, and cut it up into quarks. Its three quarks are indeed parts of the proton (quantitative parts); but they would have to come into being out of it because of a decomposing alteration.

Is there a way to decompose a proton, to alter a proton, so as to retrieve the two uquarks and the one dquark out of which it came to be? The way cannot — most certainly — be a simple quantitative division. One cannot cut up a proton with a knife. Can one decompose the proton by bombarding it in an accelerator with certain appropriate subatomic particles? But, then, can quarks be retrieved at all? Physicists say that “there can be no such thing as a free quark”? Why not? If not, then can a quark really be an element? Aren’t elements supposed to be retrievable from the

wholes of which they are parts, and thereupon capable of separate, free, existence? Were they capable of such existence in the high energy conditions “just after” the Big Bang, conditions which no longer obtain, and which physicists are trying to duplicate in their accelerator experiments?

Unlike complex bodies like wood and water, an element cannot be divided, or resolved, by alteration into bodies which are more simple than the element itself. Only prime matter and substantial form are more simple than an element, and neither one nor the other is a body; neither one nor the other has a form. If the material component(s) of what we take to be an element has a form(s), then what we have taken to be an element is not an element. The material component of an element must be absolutely formless, i.e., must be prime matter. And its formal component, therefore, must be a form which is proportioned to absolutely formless matter, i.e., a substantial form; and, at this lowly, absolutely basic level, a substantial form which manifests itself in a collection of appropriately identifying features, such as mass, electric charge, color charge, spin, baryon number.

Prime Matter Survives in One Way, the Elements in Another

Both prime matter and the elements survive in the terminus ad quem of a substantial change, but each survives differently; for what each is, is something quite different.

1) An element has a substantial form, and belongs to a species, i.e., it is a certain kind of substance. Prime matter has no substantial form.

2) An element is a natural body. Prime matter is not.

3) An element is the simplest of bodies, being composed only out of prime matter and substantial form; there are no elements in the composition of an element. Prime matter is absolutely simple, absolutely uncomposed, is not a body at all.

4) If, and to the extent that, an element can be divided (quantitatively), each resulting part must be of the same nature as the divided whole; otherwise it would not be an element. Prime matter, of itself, cannot be divided at all.

5) An element has a material component, an absolutely formless material component, i.e., prime matter. Prime matter has no material component(s); there is nothing of a material (potential, receptive) nature which is prior to prime matter.

6) An element has a formal component which is proportioned to its material component, i.e., to prime matter; its formal component is a substantial form. Prime matter has no formal component; prime matter is of itself pure potency for substantial form.

7) An element has certain active powers by which it performs its proper activities. Prime matter has no active powers at all.

Given what each is, i.e., what prime matter is and what an element is; given, secondly, that the terminus ad quem of a substantial change is a substance; and given, thirdly, that a substance can have only one substantial form, its own; it follows that prime matter survives in the newly generated substance in one way, and the elements in another way. Prime matter survives as just what it is, completely unchanged, a pure potentiality for substantial form. True, prime matter is never without a substantial form (at least that of an element); nonetheless that substantial form never becomes an ingredient of the nature of prime matter. The elements, by way of contrast, do not survive as just what they are. They do not survive, i.e., not with their substantial forms, not as the substances that they are. What survives is precisely their powers; but as changed into powers which are a kind of mean, appropriate to the newly generated substance, changed by reason of an alteration brought about by a conjunction of 1) an interaction among the relevant elements, and 2) the required agent causality of certain other things. Moreover, these mean powers are sustained in being by the substantial form of the newly generated substance, and function as the instruments through which that substance performs its proper activities. More is said about this below, on pp. 120–126, pp. 131–133, and pp. 137–143.

Concluding Reflection

20. Patet igitur ex dictis quod principium aliquomodo est in plus quam causa, et causa in plus quam elementum; et hoc est quod dicit Commentator in V Metaphysicae. 12

It is clear, therefore, from the things which have been said, that ”principle” applies in some way to more things than does “cause,” and “cause” to more things than does

“element.” And this is what the Commentator says in his comments on book five of the Metaphysics.

In 20., Aquinas reflects briefly on what he has said about principle (taken commonly) and cause and element; and notes that “principle” has a meaning which is more universal than that of “cause,” and “cause” than that of “element.” A cause is a kind of principle, for what “principle” means is part of what “cause” means. And an element is a kind of cause, for what “cause” means is part of what “element” means. And so, what “principle” means is also part of what “element” means. Every element is a cause and a principle. Every cause is a principle. But there are principles which are neither causes nor elements; and causes which are not elements.

12 Elementum enim non dicitur de causis extrinsecis, sed dicitur de intrinsecis, et dignius de materia. Principium autem est dignius dici de causis extrinsecis, et causa est maior principio in hoc. Principum etiam est quasi universalius, causa, cum dicatur principium de principiis transmutationis et de quatuor causis. (Averroes, Metaph. V, c. 3, com. 4, fol.

50a, 11.49 ss.). — From Mattingly, op. cit. , p. (25).

Chapter Four—

Relations among the Four Causes

In chapter four, St. Thomas points out many things about the four causes: the same thing can have several causes; the same thing can be the cause of contraries; the same thing can be both cause and effect in relation to a same other thing; the final cause is the cause of causes; matter is prior to form in generation and in time; form is prior to matter in substance and in completed existence; the agent is prior to the end in generation and in time; the end is prior to the agent in substance and in completed existence; matter and agent are causes which are prior in generation; form and end are causes which are prior in perfection; absolute necessity proceeds from causes which are prior in generation, that is from matter and agent; conditional necessity proceeds from causes which are posterior in generation, that is from form and end; the form, the agent and the end can coincide in some ways, because each has a measure of actuality; matter, however, cannot coincide with any of the other causes, because matter is potentiality. His comments are aimed at making clear a number of things which follow from the fact that the causes are four in number, and that each of the four is just what it is, i.e., matter: potentiality; form: actuality; agent: the active or working cause of change; end: what is intended by the agent.

An Effect Can Have More Than One Cause; and A Cause, More Than One Effect

21. Viso igitur quod quatuor sunt causarum genera, sciendum est quod non est impossibile ut idem habeat plures causas, ut idolum cuius causa est cuprum et artifex, sed artifex ut efficiens, cuprum ut materia. Non est etiam impossibile ut idem sit causa contrariorum, sicut gubernator est causa salutis navis et submersionis; sed huius per absentiam, illius per praesentiam.

Having seen, therefore, that there are four genera of causes, it should be understood that it is not impossible that a same thing have a number of causes; like a statue, the cause of which is the

bronze, and the sculptor, but the sculptor as efficient cause, and the bronze as matter. Also, it is not impossible that a same thing be the cause of contraries. The helmsman, for example, is the cause of a ship’s safety and of its sinking; of its sinking by his absence, of its safety by his presence.

In 21., Aquinas begins by observing that it is not impossible for a same thing to have more than one cause. Indeed, one should add, it is necessary for a same thing to have more than one cause. The example of Aquinas is an artifact, namely a statue, of which the bronze is the material cause, and the sculptor the efficient cause. But a natural thing, too, must have more than one cause. For example, the sperm and the ovum are the material cause of the newly conceived dog; and the parents, Lassie and King, are the efficient cause. But a thing cannot have a material cause without also having a formal cause; nor can it have an efficient cause without having a final cause. The formal cause, the canine soul (in this example), differentiates the terminus ad quem from the matter, i.e., the sperm and the ovum in this example, as that matter was found in the terminus a quo. And the final cause, a newly conceived dog, moves Lassie and King to exercise their agent causality. Without all four causes, it is not possible for an effect to come to be. Matter cannot receive form except from an appropriate agent. And the agent cannot give form to matter without the intended end.

Moreover, continues Aquinas, neither is it impossible for a same thing to be the cause of more than one effect, e.g., of contraries. The helmsman, exemplifies Aquinas, is the cause of the safety of his ship, by being present at his post and skillfully guiding the ship through a treacherously difficult and narrow passage. But he can also be the cause of the sinking of his ship — by leaving his post and letting the wind and the churning waters dash the ship against a rocky reef. Not only can a same thing be the cause of contrary effects, like safety and sinking, it can also be the cause of a plurality of effects which are not contraries. Fire, for example, can melt ice, boil water, and make one comfortable on a cold day; water can slake one’s thirst, revive a drooping

plant, cool the air on a hot and humid day. The sun can illuminate the air, and warm it as well. Indeed, it is not possible for a same thing not to have more than one effect, simply because of the variety of affectable things within the reach of its causality — one fire, close enough to ice to melt it, close enough to water to bring it to a boil, close enough to a cold person to make him comfortably warm.

An Agent Can Be Both Cause and Effect in Relation to an End; So Too Matter in Relation to Form 22. Sciendum est etiam quod possibile est ut idem sit causa et causatum respectu eiusdem, sed diversimode; ut deambulatio est causa sanitatis ut efficiens, sed sanitas est causa deambulationis ut finis; deambulatio enim est aliquando propter sanitatem. Et etiam corpus est materia animae, anima vero est forma corporis.

Efficiens enim dicitur causa respectu finis, cum finis non sit in actu nisi per operationem agentis; sed finis dicitur causa efficientis, cum non operetur nisi per intentionem finis.

Unde efficiens est causa illius quod est finis, ut puta deambulatio ut sit sanitas, non tamen facit finem esse finem, et ideo non est causa causalitatis finis, idest non facit finem esse causam finalem; sicut medicus facit sanitatem esse in actu, non tamen facit quod sanitas sit finis. Finis autem non est causa illius quod est efficiens, sed est causa ut efficiens sit efficiens. Sanitas enim non facit medicum esse medicum, et dico sanitatem quae fit operante medico, sed facit ut medicus sit efficiens. Unde finis est causa causalitatis efficientis, quia facit efficiens esse efficiens; et similiter facit materiam esse materiam, et formam esse formam, cum materia non suscipiat formam nisi propter finem, et forma non perficiat materiam nisi propter finem. Unde dicitur quod finis est causa causarum, quia est causa causalitatis in omnibus causis.

Materia etiam dicitur causa formae, inquantum forma non est nisi in materia; et similiter forma est causa materiae, inquantum materia non habet esse in actu nisi per formam. Materia enim et forma dicuntur relative ad invicem, ut dicitur

in II Physicorum.13 Dicuntur enim ad compositum sicut partes ad totum, et simplex ad compositum.

It should be understood, also, that it is possible for a same thing to be both a cause and the thing caused, with respect to a same thing, but in diverse ways. Walking, for example, is the cause of health as an efficient cause, but health is the cause of walking as an end. For a walk is sometimes taken for the sake of health. Also, the body is the matter of the soul, whereas the soul is the form of the body.

For the efficient cause is said to be a cause with respect to the end, since the end does not become something actual except through the work of the agent; whereas the end is said to be the cause of the efficient cause, since the efficient cause does not do its work except through the intention of the end. Whence the efficient cause is the cause of that which is the end; walking for example, of health. But the efficient cause does not make the end be the end. It is therefore not the cause of the causality of the end; that is, it does not make the end be the final cause. The medical doctor, for example, makes health actually be, but he does not make health be the end. The end, moreover, is not the cause of that which is the efficient cause, but rather is the cause of the fact that the efficient cause is an efficient cause. For health does not make the medical doctor be a medical doctor (I am speaking of the health which comes about by the work of the medical doctor); rather, health makes the medical doctor be an efficient cause. Whence the end is the cause of the causality of the efficient cause, because it makes the efficient cause be an efficient cause. And similarly, the end makes the matter be the matter, and the form be the form, since the matter does not acquire a form except on account of the end, and the form does not perfect the matter except on account of the end. Whence it is said that the end is the cause of causes, because it is the cause of the causality in all the causes.

Likewise, matter is said to be the cause of the form, inasmuch as the form does not exist except in matter; and similarly the form is the cause of matter, inasmuch as matter does not have actual existence except through the form. For matter and form are related to one another as mutual causes, as is said in book 13 Aristotle, Physics, Bk. II, ch. 2, 194 b 9–10.

two of the Physics; and to the composite, as parts to a whole, and as the simple to the composed.

In 22., Aquinas points out that it is possible for a same thing to be both cause and effect in relation to a same other thing, so long as it is cause with respect to one kind of causality and effect with respect to another kind of causality. This would not be possible with respect to the same kind of causality. Clearly, it would not be possible for a thing to be the efficient cause of its own efficient cause; for example, a son could not possibly be the father of his own father. Similarly, it would not be possible for a thing to be the material cause of its own material cause; for example, a statue could not possibly be the matter out of which its own matter (e.g., marble) was made.

But this is possible with respect to a different kind of causality. Walking, exemplifies Aquinas, is both the cause of, and caused by, health. Or, perhaps more clearly, walking is the cause of health, and health is the cause of walking. But, whereas walking is the efficient cause of health, health is not the efficient cause of walking. It is rather the final cause of walking. Similarly, continues Aquinas, the body is both the cause of, and caused by, the soul. Or, the body is the cause of the soul, and the soul is the cause of the body. But, whereas the body is the matter in which the soul exists, the soul is not the matter in which the body exists. It is rather the form which vivifies the body. Whereas the body is cause as matter, the soul is cause as form. And this does not mean that the body is the matter of the soul, as though it were a part of the nature of the soul. Nor does it mean that the soul is the form of the body, as though it were a part of the nature of the body. Rather, the body and the soul are the matter and the form, respectively, of the nature of the composite, i.e., of the whole which is the living thing, e.g., a human being.

Moreover, the reciprocal or mutual causal connection between the efficient cause and the final cause must be properly understood. The efficient cause is the cause of the thing which is the end, e.g., walking is the cause of health.

But the efficient cause does not cause the end to be the end. That is, it is not the cause of the causality of the end. The medical doctor, for example, causes the health which is the end, but he does not cause the health to be the end. Further, the end is not the cause of the thing which is the efficient cause; it is rather the cause of the fact that the thing which is the efficient cause is the efficient cause. For example, health does not cause the medical doctor to be a medical doctor — Aquinas is speaking here explicitly of the health which comes about by the efforts of the medical doctor; rather, health causes the medical doctor to be an efficient cause. And so, the end is the cause of the causality of the efficient cause, inasmuch as it makes the thing which is the efficient cause to be precisely that, i.e., the efficient cause. And beyond that, the end makes the matter (material cause) to be the material cause, and the form (formal cause) to be the formal cause. And this is so because the matter acquires the form only for the sake of the end, just as the form perfects the matter only for the sake of the end. This is why it is said that the end is the cause of causes, meaning that the final cause causes the causality in all the causes, i.e, in the other three causes.

But what, one might ask, causes the causality of the end? What is it that makes the end to be the end? The efficient cause does not make the end to be the end, as already noted. And since that is so, neither does the matter cause the causality of the end; and neither does the form; since it is the end which causes their causality.

Shall we say, then, that the causality of the end is an uncaused causality? This seems the right thing to say. For, from one point of view, there are no other causes besides the other three, which could possibly cause the causality of the end; and the other three cannot, as just noted. And, from another point of view, the final cause would be the cause of its own causality, by circularity. That is, the end would cause the agent to be the agent, which would cause the matter to be the matter, which would cause the form to be the form. And the form would have to cause the end to be the end; for there is no other kind of cause. But nothing can be the cause of its own causality.

The Matter and the Agent Are Both Prior and Posterior to the Form and the End

23. Sed quia omnis causa, inquantum est causa, naturaliter prior est causato, sciendum est quod prius dicitur duobus modis, ut dicit Aristoteles in XVI De Animalibus, 14 per quorum diversitatem potest aliquid dici prius et posterius respectu eiusdem et causa causatum. Dicitur enim aliquid prius altero generatione et tempore, et iterum in substantia et complementum. Cum ergo operatio naturae procedat ab imperfecto ad perfectum et ab incompleto ad completum, imperfectum est prius perfecto secundum generationem et tempus, sed perfectum est prius imperfecto substantia; sicut potest dici quod vir est ante puerum in substantia et complemento, sed puer est ante virum in generatione et tempore. Sed, licet in rebus generabilibus imperfectum sit prius perfecto et potentia prior actu, considerando in aliquo eodem quod prius est imperfectum quam perfectum et in potentia quam in actu, simpliciter tamen loquendo oportet actum et perfectum prius esse; quia quod reducit potentiam ad actum, actu est et quod perficit imperfectum, perfectum est. Materia quidem est prior forma generatione et tempore; prius enim est cui advenit, quam quod advenit. Sed forma est prior materia in substantia et completo esse, quia materia non habet esse completum nisi per formam. Similiter efficiens est prius fine generatione et tempore, cum ab efficiente fiat motus ad finem; sed finis est prior efficiente inquantum est efficiens in substantia et complemento, cum actio efficientis non compleatur nisi per finem. Igitur istae duae causae, scilicet materia et efficiens, sunt prius per viam generationis; sed forma et finis sunt prius per viam perfectionis.

Every cause, insofar as it is a cause, is naturally prior to what is caused. This is why it should be understood that “prior” is said in two ways, as Aristotle says in book sixteen of On Animals. And it is through the diversity of these two ways that something can be said to be prior and posterior in relation to a same thing, 14 Aristotle, De Gen. Animal., Bk. II, ch. 6, 742 a 19–22. — As Pauson ( op. cit. , p. 69) points out, Aquinas’ reference to chapter XVI indicates that he was using the ArabLatin translation, usually entitled De Animalibus, in which the order of the books is: De Historiis Animalium, I–X; De Partibus Animalium, XI–XIV; and De Generatione Animalium, XV–XIX.

and a cause can be said to be something caused. For a thing is said to be prior to another in generation and time, and again in substance and completeness. Since, therefore, the operation of nature proceeds from the imperfect to the perfect and from the incomplete to the complete, the imperfect is prior to the perfect in generation and time, but the perfect is prior to the imperfect in substance. It can be said, for example, that the man is before the boy in substance and completeness, whereas the boy is before the man in generation and time. But, although in generable things the imperfect is prior to the perfect, and potency is prior to act (considering that in one and the same thing the prior is imperfect rather than perfect, and in potency rather than in act); nonetheless, absolutely speaking, it is necessary that what is in act and perfect be prior; because what brings potency to act is itself in act, and what perfects the imperfect is itself perfect. Matter, indeed, is prior to form in generation and time; for that to which something comes, is prior to that which comes to it.

But form is prior to matter in substance and completeness of existence, because matter has completeness of existence only through form. Similarly, the efficient cause is prior to the end in generation and time, because the motion toward the end comes from the efficient cause. But the end is prior to the efficient cause, insofar as it is the efficient cause, in substance and completeness, since the action of the efficient cause is completed only through the end. These two causes, therefore, namely the matter and the efficient cause, are prior in the way of generation; but the form and the end are prior in the way of perfection.

In 23. , St. Thomas begins by observing that although a cause, as cause, is prior by nature to what it causes; nonetheless, because the word “prior” has two different uses, one and the same thing can be both prior and posterior, and both cause and effect, in relation to a same other thing. The two uses of the word “prior” are these: 1) with respect to generation and time, which can be taken to mean: with respect to coming into existence, and 2) with respect to substance and completeness, which can be taken to mean: with respect to existence. The operation of nature, it is easy to observe, moves from what is imperfect and incomplete to what is perfect and complete. To speak of the operation of nature is to speak of generation; and generation takes time, i.e., it begins and ends. For example, the boy comes to be before

the man comes to be; and so, the boy is prior to the man with respect to generation and time. But the man is perfect and complete in a way in which the boy is not;

and so, the man is prior to the boy with respect to human substance and completeness of being.

In one and the same generable thing, continues Aquinas, the imperfect and potential is observed to be prior to the perfect and actual. Indeed, this is how it must be. But, absolutely speaking, i.e., outside the context of one and the same generable thing, what is perfect and in act is prior to what is imperfect and in potency. And this is so because only what is perfect and actual can bring what is imperfect and potential to a state of perfection and actuality. Matter, thus, in the context of one and the same generable thing, is prior to form with respect to generation and time; for form comes to matter, and that to which something comes is already in existence, i.e., prior in time to that which comes to it. But, the form is prior to matter in substance and completeness of existence; that is, matter acquires completeness of existence only through the form.

Similarly, continues Aquinas, the efficient cause is prior to the end in generation and time; that is, the motion toward the end comes from the efficient cause which is already in operation, temporally before the end comes into existence. But, the end is prior to the efficient cause in substance and completeness of existence. This must be properly understood. It is not being said that the completely existing end is prior, as actually existing, to the action of the efficient cause. The statue which the sculptor is about to make, for example, does not actually exist before the sculptor begins to make it. For this would be to say that the statue exists before it exists;

which is clearly impossible. What is being said is that the completion of the action of the efficient cause is found only in the actually existing statue; that is, that the action of the efficient cause continues until the end has begun to exist. And so, the actual existence of the end is the completion of the efficient causality of the agent; just as the actual existence of the form is the completion of the material causality of the matter.

Why this concern, one might ask, to point out that the matter and the efficient cause are prior in generation and time, whereas the form and the end are prior in substance and perfection (or completeness of existence)? The answer, it appears, is provided in 24. (to which we now turn), where Aquinas reflects on the kinds of necessity found in the physical world, i.e., absolute necessity and conditional necessity.

Absolute Necessity and Conditional Necessity

24. Et notandum quod duplex est necessitas, scilicet absoluta et conditionalis. Necessitas quidem absoluta est, quae procedit a causis prioribus in via generationis, quae sunt materia et efficiens; sicut necessitas mortis quae provenit ex materia, scilicet ex dispositione contrariorum componentium; et haec dicitur absoluta, quia non habet impedimentum.

Haec etiam dicitur necessitas materiae. Necessitas autem conditionalis procedit a causis posterioribus in generatione, scilicet a forma et fine; sicut dicimus quod necessarium est esse conceptionem, si debeat generari homo. Et ista dicitur conditionalis, quia hanc mulierem concipere non est necessarium simpliciter, sed sub hac conditione, scilicet si debeat generari homo. Et haec dicitur necessitas finis.

It should be noted that necessity is of two sorts, namely absolute and conditional. Now absolute necessity is the necessity which proceeds from causes which are prior in the way of generation, which are the matter and the efficient cause. The necessity of death, for example, derives from matter, i.e., from the disposition of the composing contraries. And this necessity is said to be absolute, because it has no impediment. It is also called the necessity of matter. Conditional necessity, however, proceeds from causes which are posterior in generation, namely from the form and the end. We say, for example, that conception is necessary, if a man is to be generated. And this necessity is said to be conditional, because it is not simply necessary that this woman conceive, but under this condition,

namely if a man is to be generated. And this necessity is called the necessity of the end.

In 24. , Aquinas points out that there are two kinds of necessity. There is 1) absolute necessity when something must come to be because something else has preceded — unless (Aquinas adds elsewhere, as in In VI Metaph., lect 3, n. 1193 and n. 1217) something else is there to prevent it, like a freely acting human agent.

There is 2) conditional necessity when something must come to be because without it something else cannot follow, i.e., if — indeed only if — that something else is to follow. There is no reason, other than the following of the posterior, why the prior has to come to be. Absolute necessity, he observes, derives from causes which are prior in generation, i.e., from the matter and the agent; but it resides in what is posterior. Conditional necessity derives from causes which are posterior in generation, i.e., from the form and the end; but it resides in what is prior. Given such and such a matter, or such and such an agent, something (i.e., some form or some end) must follow. But, if — only if, hence under a condition — this form is to come to be, or this end is to be achieved, then there must be (beforehand) such and such a matter, or such and such an agent. But, apart from that condition, there is no need at all for that matter or for that agent to have preceded.

Having noted that absolute necessity derives from causes which are prior in generation, namely matter and agent, Aquinas offers an example of necessity deriving from matter, i.e., the necessity of death. Death is absolutely necessary, because of the disposition of the contraries which compose the body of a living thing, i.e., because of the tendency of the composing contraries to act in a certain way under certain conditions. But he gives no example of absolute necessity deriving from the agent. Is there a reason for not giving such an example? Similarly, having noted that conditional necessity derives from causes which are posterior in generation, namely form and end, Aquinas offers an example of necessity deriving from the end, i.e.,

the necessity of conception. Conception is conditionally necessary, because of the generation of a man, i.e., if a man is to be generated. But he gives no example of necessity deriving from the form. Is there a reason for not giving such an example? Can it be that absolute necessity derives somehow from the matter and the agent together? And that conditional necessity derives somehow from the end and the form together?

This might well be the case. Consider that the end of the agent is to act in such a way as to confer a certain sort of form on a certain sort of matter. And so, the end is the form. Thus, the necessity which is said to derive from the end, can be said to derive from the form as well. To say: if this end is to be achieved, is the same as to say: if this form is to come to be. Thus, form and end together are the source of conditional necessity, but not as though the form were one thing and the end another;

the form and the end are one and the same thing.

Consider, further, that a certain sort of matter must receive a certain sort of form, when a certain sort of agent is acting on it. And so, although the matter and the agent are not the same thing (though the form and the end are the same thing), given such an agent acting on such a matter, such a form must be the result. The necessity, for such a form, which derives from the matter, derives from it only in conjunction with the appropriate agent. The source of absolute necessity is the matter, indeed, but together with, and as being affected by, the agent. — And so, given such a matter being affected by such an agent, such a form (such an end) must follow, out of absolute necessity. And, if (only if) such a form (such an end) is to come to be, then such a matter, being affected by such an agent, must precede, out of conditional necessity.

The Necessity of Death

It will be helpful at this point to reflect a bit on Aquinas’ example of absolute necessity. This may help to make clearer exactly what absolute necessity is. His example, recall, was the necessity of death, a necessity deriving from matter, i.e., from the fact that a living thing is made up of components which are contraries: … sicut necessitas mortis quae provenit ex materia, scilicet ex dispositione contrariorum componentium …. It is quite clear that when Aquinas says ”composing contraries,” he means “composing elements.” Now, each of the elements has a distinguishing quality or property. Fire is hot; heat is the distinguishing property of fire.

Air is dry, water wet, and earth cold. Hot and cold are contraries. Wet and dry are contraries. When the cold and the dry overcome the hot and the wet, death occurs. Life needs the hot and the wet. So that when a living thing is not hot (warm) enough, nor wet (moist) enough, it dies. Hypothermia alone, as well as dehydration alone, can bring on death. The two together can bring on death all the more quickly and certainly. Similarly, when the hot and the wet overcome the cold and the dry, death occurs. Life needs the cold and the dry. So that when a living thing is not cold enough, i.e., when it is too hot; or when it is not dry enough, i.e., when it is too wet, it dies. Hyperthermia (e.g., high fever) alone, as well as hyperhydration (too much water) alone, can bring on death. And the two together can bring on death all the more quickly and certainly.

Furthermore, the elements are intrinsically, and so necessarily, corruptible, because they are composed of prime matter and substantial form. It follows, therefore, that mixed bodies too, i.e., bodies composed of the elements, are intrinsically, and so necessarily, corruptible. For, as Aquinas puts it: … corruptis componentibus, corrumpitur compositum … ( In II Sent. , d.16, q.1, a.1 ad 3).

Again, it is necessary for a human being, indeed for any living thing, to die, because matter is in potency to another form: … homini … convenit Page 70

necessitas moriendi, ex hoc scilicet quod materia est in potentia ad aliam formam … ( De Malo, q.5, a.5, ad 13). And matter is in potency to other forms, precisely because it is first in potency to the forms of the elements, i.e., the contraries, which compose the body of a living thing.

Moreover, when one element overpowers another with its distinguishing quality or property, what follows is the corruption of the overpowered one and the generation and/or augment of the overpowering one. It is only when the powers of the elements have been rendered, and continue to be, more or less equal to one another (when they more or less balance one another, or are more or less in a state of equilibrium) that there comes to be, and continues to be, a mixed body, either a living one or a nonliving one.

Someone might say that being composed of elements does not make corruption (which is death for a living thing) necessary, but only possible. It is quite clear that what is composed can fall apart. But must it fall apart? If something must, it can. But, is it true that if something can, it must? — By way of response, one must note that the necessity of death, according to Aquinas, derives “from the disposition of the composing contraries.” Not simply from the fact that there is a composition, nor even from the fact that the composition is out of contraries (elements). Rather, from the disposition (ex dispositione) of the composing contrary elements. And

“disposition” means a tendency or inclination to act or behave in a certain way under certain conditions. Under certain conditions, the heat of fire can overcome the cold of earth; and when it does, death occurs. Or the dryness of air can overcome the wetness of water; and when it does, death occurs. Thus the nature or essence of a living mixed body, inasmuch as it is composed of elements, is such that it is necessarily corruptible, necessarily capable of death. And under certain conditions, it does corrupt, it does die. Thus, to speak of the necessity of death, … necessitas mortis … , is to speak of the necessity of the possibility of death, and not of the actual fact of death. Aquinas puts it clearly and explicitly for the careful reader: … sicut dicimus animal necesse esse corruptibile [notice: necessarily corruptible], quia hoc consequitur eius

materiam inquantum ex contrariis componitur … ( In V Metaph. , lect. 6, n. 833).

Again, someone might ask why Aquinas says here that absolute necessity has no impediment. Elsewhere he observes that an effect follows necessarily because its cause has preceded, unless there is an impediment: … necesse est, … causa posita, sequi effectum, nisi sit impedimentum … ( In VI Metaph. , lect. 3, n.

1193). — By way of response, one must note that there is no possibility of an impediment to the necessity of the possibility of death for a living mixed body once constituted in being, for such a body has such a necessity by its very essence, inasmuch as it is composed out of contraries (elements). And its being composed out of contraries is the causa posita. But there is the possibiliy of an impediment to the actual death, at some given time, of a living mixed body, inasmuch as there are any number of agent causes in the physical world which can at a given time prevent its death: … unde … [etiam causis] positis, adhuc potest impediri effectus, propter occursum . . agentis… . ( In VI Metaph. , lect. 3, n. 1191).

Three of the Causes — Form, End, Agent — Can Coincide with One Another; The Fourth, i.e., Matter, Cannot Coincide with any of the Other Three 25. Et est sciendum quod tres causae possunt incidere in unum, scilicet forma, finis et efficiens, sicut patet in generatione ignis. Ignis enim generat ignem, ergo ignis est causa efficiens inquantum generat; et iterum ignis est forma inquantum facit esse actu quod prius erat potentia; et iterum est finis inquantum est intentus ab agente, et inquantum terminatur ad ipsum operatio agentis.

Sed duplex est finis, scilicet finis generationis et finis rei generatae, sicut patet in generatione cultelli; forma enim cultelli est finis generationis, sed incidere quod est operatio cultelli, est finis ipsius generati, scilicet cultelli.

Finis autem generationis coincidit cum duabus dictis causis aliquando, scilicet quando fit generatio a simili in specie; sicut Page 72

homo generat hominem, et oliva olivam, quod non potest intellegi de fine rei generatae. Sciendum tamen est quod finis incidit cum forma in idem numero, quia illud idem numero quod est forma generati, est finis generationis. Sed cum efficiente non incidit in idem numero, sed in idem specie. Impossibile enim est ut faciens et factum sint idem numero, sed possunt esse idem specie; ut quando homo generat hominem, homo generans et generatus sunt diversi numero, sed idem specie.

Materia autem non coincidit cum aliis, quia materia ex eo quod est ens in potentia, habet rationem imperfecti; sed aliae causae, cum sint actu, habent rationem perfecti; perfectum autem et imperfectum non coincidunt in idem.

It should be understood that three of the causes — namely the form, the end, and the efficient cause — can coincide in a thing in some way one, as is clear in the generation of fire. For fire generates fire. And so, fire is the efficient cause, insofar as it generates. Fire is also the form, insofar as it makes that which was formerly in potency to be in act. It is also the end, insofar as it is intended by the agent, and insofar as the operation of the agent terminates in it.

But there are two sorts of end, namely the end of generation, and the end of the generated thing, as is clear in the generation of a knife. For the form of the knife is the end of generation; but cutting, which is what the knife does, is the end of the generated thing, namely of the knife.

At times the end of generation coincides with the other two mentioned causes [namely the form and the efficient cause]. This happens when generation takes place from a thing which is alike in species; as when a man generates a man, and an olive tree an olive tree. But this cannot be the case with respect to the end of the generated thing. It should be understood, nonetheless, that the end [of generation] coincides with the form, in a thing one in number, because the numerically one thing which is the form of the generated thing is the end of generation. But the end [of generation] does not coincide with the efficient cause in a thing the same in number; rather in a thing the same in species. For it is impossible for the maker and the thing made to be the same in number, but they can be the same in species. When a man generates a man, for example, the Page 73

man generating and the man generated are diverse in number, but the same in species.

Matter, however, does not coincide with the others; because matter, by the fact that it is a being in potency, has the nature of something imperfect, whereas the other causes, since they are in act, have the nature of something perfect. The perfect and the imperfect do not coincide in a same thing.

In 25., Aquinas points out that something one and the same (one and the same, in some sense or other) can be the agent and the end and the form all three. He begins with the example of the generation of fire. Fire generates fire. And so, as generating, fire is the efficient cause. And as generated, fire is both the form and the end.

Inasmuch, as generated, it makes what can be on fire, i.e., some combustible material, to be actually on fire, it is the form. Inasmuch, as generated, it is also what is intended by the agent, and is that in which the work of the agent is terminated, it is the end.

Having given the example of fire, Aquinas notes next that there are two kinds of end: 1) the end of the process of generation, and 2) the end of the thing which has been generated. To clarify, he uses the production of a knife as an example. The form of the knife is the end of the process of generation, i.e., of the process of the production of the knife; whereas cutting is the end of the thing generated, i.e., of the knife itself. He makes this distinction in order to be able to point out that when something the same is the agent and the form and end, all three; it is the end in the sense of the end of the process of generation, and only when like is generated by like, as man by man, or an olive tree by an olive tree, or fire by fire. This cannot happen when like is not generated by like, as in the case of a knife by the knife maker.

Clearly, the end of the process of generation, e.g., the form which is the sharpness of the blade of the knife, cannot in any way be the same as the knife maker himself.

Neither can this happen when the end is the end of the generated thing. The cutting to be done by the knife, for example, cannot in any way be the same as the knife maker himself.

Moreover, continues Aquinas, the end of generation is the same in number as the form, i.e., the very thing which is the form of the generated thing is the same, numerically the same, as the end of generation. But, the end of generation is not the same, not numerically the same, as the efficient cause. Indeed, this is not possible;

the maker, for example, cannot be numerically identical with the thing made. They can, however, be identical in species, as when a man generates a man. The man generating and the man generated are diverse in number, emphasizes Aquinas, but the same in species.

Lastly, concludes Aquinas, matter cannot coincide with any of the other three causes, simply because matter has the nature of something imperfect; it is a being in potency. The agent, the form, and the end, by way of difference, are beings in act, and so have the nature of something perfect. It is impossible for the perfect and the imperfect to coincide so as to be a same thing. Or, one and the same thing cannot be both perfect and imperfect in the same respect. Or, that which can be, cannot be that which is; just as that which is not, cannot be that which is.

Chapter Five—

Divisions within Each of the Four Causes

In chapter five, St. Thomas points out, and makes clear, a number of ways in which each of the four kinds of cause — efficient, material, formal, final — can be divided. A cause can be a cause in a prior sense or in a posterior sense; a cause can be remote or proximate, per se or per accidens, simple or composite, actual or potential, universal or singular. His comments are aimed at making clear how effects can be acceptably explained by their causes. That is, not just any cause can be used to explain an effect; a cause ought to be proportioned to its effect. For example, actual effects are to be explained by actual causes, universal effects by universal causes, singular effects by singular causes. Above all, every explanatory attempt should seek the first cause — “… semper debemus reducere quaestionem ad primam causam … “. An explanation which does not include the first cause is not a complete explanation; for one must still ask: Why? This is so because a cause which is not a first cause is also an effect, and as an effect, needs to be explained.

Prior Causes and Posterior Causes

26. Viso igitur quod sunt quatuor causae, scilicet efficiens, materialis, formalis et finalis, sciendum est quod quaelibet istarum causarum dividitur multis modis. Dicitur enim aliquid causa per prius et aliquid per posterius, sicut dicimus quod ars et medicus sunt causa sanitatis, sed ars est causa per prius, medicus per posterius; et similiter in causa formali et in aliis causis. Et nota quod semper debemus reducere quaestionem ad primam causam, ut si quaeratur: quare iste est sanus? respondendum est: quia medicus sanavit; et iterum: quare medicus sanavit? propter artem sanandi quam habet.

Having seen therefore that there are four causes, namely efficient, material, formal and final, it should be understood that each of these causes is divided in many ways. For some Page 76

things are called causes in a prior sense, others in a posterior sense. We say, for example, that art and the medical doctor are causes of health; but art in a prior sense, and the medical doctor in a posterior sense. And similarly with respect to the formal cause, and the other causes. Note, too, that we should always take a question all the way back to the first cause. If it be asked, for example, “Why is this person healthy “? one should answer, “Because the medical doctor has restored him to health.” And, asking further, “Why did the medical doctor restore him to health?” one would answer, “Because of the art of healing which he has.”

Aquinas begins 26. by observing that each of the four causes can be divided in a number of ways. Having made that observation, he points out a first division, that into causes in a prior sense and causes in a posterior sense. Then he uses the efficient cause as an example. Both art and the medical doctor are efficient causes of health;

but the medical doctor in a posterior sense, he notes, and art in a prior sense. Aquinas does not make explicit, however, the sense of “prior” and “posterior” which he has in mind. Does he mean prior and posterior in time? in power? in universality? In some other sense? In what sense of “prior” is the art of healing, which the medical doctor has, a cause which is prior to the medical doctor himself? It would seem that there is no priority here, since the medical doctor is a medical doctor precisely by reason of the art of healing which is in him. Moreover, as in him, the art of healing seems to be a formal cause rather than an efficient cause. But, if it is an efficient cause, then it is something in the medical doctor, i.e., that in the medical doctor by which he can perform as a medical doctor; and so, again, not prior to him.

Remote Causes and Proximate Causes:

The Same As Prior Causes and Posterior Causes, Respectively

27. Sciendum est etiam quod idem est dictu causa propinqua quod causa posterior, et causa remota quod causa prior. Unde ista duae divisiones: causarum alia per prius, alia per posterius,

et causarum alia remota, alia propinqua, idem significant. Hoc autem observandum est quod semper illud quod universalius est, causa remota dicitur; quod autem specialius, causa propinqua; sicut dicimus quod forma hominis propinqua est sua definitio, scilicet animal rationale mortale; sed animal est magis remota et iterum substantia remotior. Omnia enim superiora sunt formae inferiorum. Et similiter materia idoli propinqua est cuprum, sed remota est metallum, et iterum remotior corpus.

It should be understood that to speak of a proximate cause is the same as to speak of a posterior cause, and of a remote cause the same as of a prior cause. Whence these two divisions: some causes are prior, others posterior; some causes are remote, others proximate, come to the same thing. Moreover, it should be observed that the cause which is more universal is always called the remote cause, whereas the one which is more particular, the proximate cause; as when we say that the proximate form of man is his definition, namely rational mortal animal; whereas animal is more remote, and substance more remote still. For all the superiors are forms of the inferiors. Similarly, the proximate matter of a statue is bronze, whereas a remote matter is metal, and a more remote matter still is body.

In 27., Aquinas moves on to a second division, that into remote causes and proximate causes. He begins by pointing out that proximate causes are the same as the posterior causes considered in 26., and remote causes the same as the prior causes of 26. . And so, the first two divisions of cause come to the same thing.

Then he explains that the cause which is more universal is always called the remote cause. And having already observed that a remote cause is the same as a prior cause, Aquinas has in effect answered the question raised above (p. 76) about exactly what he means by “prior” and “posterior.” It is clear now that he means prior and posterior in universality. His examples confirm this: substance, in the realm of the formal cause (with respect to man), is more universal than animal, which is in turn more universal than

rational mortal animal; body, in the realm of the material cause (with respect to statue), is more universal than metal, which is in turn more universal than bronze.

Similarly, one might add, one who works by an art which is in him (artifex), in the realm of the efficient cause (of health), is more universal than medical doctor.

Which suggests that Aquinas might better have said “artifex” than “ars.” Artifex — but not ars — is related to medicus as the more universal (hence, as the prior or the more remote) to the more particular or less universal (hence, as the posterior or the more proximate). A medicus is a kind of artifex, but not a kind of ars. 15

Having given ars and medicus, in 26., as examples of efficient causes related as the prior to the posterior, Aquinas had added, “… et similiter in causa formali et in aliis causis … “. In 27., he gave an example of formal causes related as the prior to the posterior, namely substantia, animal, and animal rationale mortale; and of material causes similarly related, namely corpus, metallum, and cuprum. He did not give an example of final causes so related. For the sake of a kind of completeness, the following example might be acceptable, namely qualitas, dispositio, sanitas, moving from the prior to the posterior, as the goal or final cause of the work of the medical doctor. And as an example of form, or formal cause, in the sense of forma partis, one might suggest forma substantialis, anima, anima rationalis, moving from the prior to the posterior, as the formal cause of man.

Semper Debemus Reducere Quaestionem Ad Primam Causam

It is not wholly clear what Aquinas means by saying that “we should always take a question all the way back to the first cause” (p. 69, 26. ); though it is clear why one should do this, namely to have a complete explanation. For a cause which is not a first cause is also an effect, and as an effect, needs to be explained — as was said above (p. 69).

15 See Pauson, op. cit. , footnote 1, pp. 98–99.

On first reading, it seems he has in mind a series of different things, each of which is both the same kind of cause — either efficient, or formal, or final, or material, depending on the sort of explanation being given — and is more universal than its predecessor in the scope of its causal power, so that the first cause is a thing with the most universal possible causal scope. But, a consideration of his examples seems to indicate something different. As Aquinas’ examples move from the proximate (posterior, less universal) cause to the remote (prior, more universal) cause, one sees that the series is not a series of different things at all, but rather that one and the same thing is being designated at different levels of universality. Bronze, which is the proximate material cause of the statue, can be called metal and body. And it is not the case that metal is the material cause of bronze, and body the material cause of metal, in the same sense in which bronze is the material cause of the statue.

Rather, body and metal and bronze — all three — are the one material cause of the statue. They are not three different material causes in series; they are the same material cause, though differently described, i.e., body describes the material cause in a more universal way than metal does, and metal in turn in a more universal way than bronze does.

The same thing is the case in Aquinas’ example of substantia, animal and animal rationale mortale as the formal causes (in the sense of forma totius) of man. The same thing is also the case in the example of artifex and medicus as the efficient causes of health; in the example of qualitas, dispositio, and sanitas as the final causes of the work of the medical doctor; and in the example of forma substantialis, anima, and anima rationalis as the formal causes (in the sense of forma partis) of man. In all these examples, it is quite clear that the universals, the more and the lesser as well, are predicable universals, i.e., universals in praedicando, and not causal universals, i.e., not universals in causando. And, on first reading, one would have expected them to be just that, i.e., universals in causando.

In what sense, if any — one might ask — do more universal predicable universals serve to complete the explanation given by less universal predicable universals?

That is, what is more complete about saying that metal is the material cause of the statue than saying that bronze is; and what is more complete still about saying that body is the material cause of the statue than saying that metal is? Metal, as was said above, is not that out of which bronze is made, in the sense in which the statue is made out of bronze. Nor is body that out of which metal is made, in that same sense. Rather, the concept of metal is a material component of the concept of bronze, and the concept of body is a material component of the concept of metal — material component in the sense of a concept which is open to, potential to, specification by a differentiating concept. The concept of body is open to being specified by a differentiating concept which, when added to the concept of body, provides the concept of metal. Similarly, the concept of metal is open to being specified by a differentiating concept which, when added to the concept of metal, provides the concept of bronze.

If one goes the other way now, i.e., from the less universal to the more universal, beginning with the question, “What is the material cause of the statue?” one will be able to see how a more universal predicable universal completes the explanation given by a less universal one. The completion amounts to clarification, by way of explicit additions of superior genera and their differences. Having answered that bronze is the material cause of the statue, one then asks, “What exactly is bronze?”

And one answers that bronze is a kind of metal, metal being a genus of bronze. Then one asks, “What is metal?” One answers that metal is a kind of body, body being another, and more universal, genus of bronze. Then, “What kind of metal is bronze?” The answer here will provide the specific difference of bronze. Then, “What is a body?” The answer, “A body is a kind of substance,” provides the genus of body. Then, “What kind of body is metal?” The answer here will provide the specific difference of metal. — One can see that

the movement here is a movement up the Tree of Porphyry; and that when one has come to the top of the tree, one has a complete answer, i.e., an explicitly clarified answer, to the question, “What is bronze?” which is also a complete answer, i.e., an explicitly clarified answer, to the question, “What is the statue made out of?” or,

“What is the material cause of the statue?” One has given an explicitly clarified account of the nature of bronze.

Now, there is another way to answer the question, “What is the material cause of the statue?” or, “What is the statue made out of?” a way which asks for material causes of material causes, rather than asking for more universal predicable universals whose function is to clarify. The material cause of the statue is bronze, or the statue is made out of bronze. Bronze is made out of copper (Cn) and tin (Sn). Copper (tin, too) is one of the elements, and an atom of copper (of tin, too) is made out of neutrons, protons, and electrons. And these in turn are made ultimately out of quarks. And here, in quarks, we have come — at least as far as our present knowledge takes us — to the first material components of physical things. If the quark is, indeed, the first material component, the question, “What is a quark?” will be answered by saying that it is something made out of prime matter and a substantial form of a certain sort, to be described in terms of a reference to what a quark does.

Causes per se and Causes per accidens

28. Item causarum alia est per se, alia per accidens. Causa per se dicitur, quae est causa alicuius rei inquantum huiusmodi; sicut aedificator est causa domus et lignum materia scamni. Causa per accidens dicitur illa quae accidit causae per se, sicut cum dicimus quod grammaticus aedificat. Grammaticus enim dicitur causa aedificationis per accidens, non enim inquantum grammaticus, sed inquantum aedificatori accidit quod sit grammaticus. Et similiter est in aliis causis.

Again, some causes are causes because of themselves (per se), and others are causes because of something which has happened Page 82

to them (per accidens). A cause is said to be a cause per se when it, precisely as such, is a cause of something. For example, a builder [precisely as such, i.e., as a builder] is the cause of a house, and the wood [precisely as such, i.e., as wood] is the matter of the bench. A cause is said to be a cause per accidens when it happens to be conjoined to that which is a cause per se, as when we say that the grammarian builds. The grammarian is said to be the cause of the building per accidens, i.e., not inasmuch as the grammarian is a grammarian, but inasmuch as it happens to the builder that the builder is a grammarian. And similarly for the other causes.

In 28., Aquinas reflects briefly on a third division of causes, that into per se causes and per accidens causes. A per se cause is a cause such that its effect depends on that cause taken precisely as such, i.e., according to what it is. For example, a builder taken precisely as such, that is, according to what he is, i.e., a builder, is the efficient cause of the houses he builds. And wood taken precisely as such, that is, according to what it is, i.e., wood, is the material cause of the statues which have been made out of wood. A per accidens cause, on the other hand, is a cause such that what is said to be its effect can be said to depend on it, but not taken as such — taken rather according to some conjoined characteristic which it happens to have, and by reason of which it is the per se cause of that effect. For example, a medical doctor can be said to be the efficient cause of the houses he builds, but these houses do not depend on the medical doctor taken precisely as such, that is, according to what he is, i.e., a medical doctor. Rather, these houses depend on the medical doctor only, and precisely, because the medical doctor is also, happens to be (accidit), a builder. This man is a man with at least two skills or arts, that of a medical doctor and that of a builder. And there is no reason why one cannot say that the medical doctor is the efficient cause of the houses he builds, so long as he is also a builder, and so long as it is understood that he is the efficient cause precisely as builder, and not as medical doctor. — As another example, this hot thing, or this cold thing, can be said to be the material cause of the statue which has been made out of it. But the statue

does not depend on this hot thing (or on this cold thing), taken as such, that is, according to what each is, i.e., a hot thing or a cold thing. Rather, the statue depends on the hot thing, or the cold thing, precisely because each is also, each happens to be (accidit), wood. This piece of material is a piece of material with at least two features or attributes: 1) that of being wood, and 2) that of being hot (or cold). And there is no reason why one cannot say that this hot thing (or this cold thing) is the material cause of the statue, so long as it is also a piece of wood, and so long as it is understood that it is the material cause precisely as wood, and not as hot thing (or cold thing).

One can see quite readily that effects are properly explained only by their per se causes; not by their per accidens causes. The per accidens causes are irrelevant, and possibly countless in number. One can also see that, when one speaks of suchandsuch as being the cause of suchandsuch other, one always means per se cause, even though he does not explicitly say that he means per se cause. One can also see that it is important to keep in mind the distinction between per se cause and per accidens cause, in order to avoid being misled in one’s atttempt at an explanation. If one gets drunk on water mixed with bourbon on Monday, on water mixed with scotch on Tuesday, on water mixed with rye whiskey on Wednesday, on water mixed with gin on Thursday, on water mixed with vodka on Friday, one most be careful not to conclude that it is water which has caused the drunkenness as a per se cause.

Simple Causes and Composite Causes

29. Item causarum quaedam est simplex, quaedam composita. Simplex causa dicitur quando solum dicitur causa illud quod per se est causa, vel etiam solum illud quod est per accidens; sicut si dicamus aedificatorem esse causam domus, et similiter si dicamus medicum esse causam domus. Composita autem dicitur quando utrumque dicitur causa, ut si dicamus: aedificator medicus est causa domus. Potest etiam dici causa

simplex, secundum quod exponit Avicenna:16 illud quod sine adiunctione alterius est causa, sicut cuprum idoli — sine adiunctione enim alterius materiae ex cupro fit idolum — et sicut dicitur quod medicus facit sanitatem, vel quod ignis calefacit. Composita autem causa dicitur quando oportet plura advenire ad hoc quod sit causa; sicut unus homo non est causa motus navis, sed multi; et sicut unus lapis non est materia domus, sed multi.

Further, some causes are simple, others are composite. A cause is said to be a simple cause when that alone, which is the per se cause, is said to be the cause, as if we were to say that the builder is the cause of the house; or that alone which is the per accidens cause, as if we were to say that the medical doctor is the cause of the house. A cause is said to be a composite cause when both are said to be the cause, as if we were to say that the buildermedical doctor is the cause of the house. — A cause can also be called a simple cause, according to the account given by Avicenna, when it is such that it is a cause without anything else being added to it; as bronze is the cause of the statue, for the statue is made out of bronze without the addition of any other matter; and as when it is said that the medical doctor brings about health, or that fire heats. A cause is said to be a composite cause, on the other hand, when a number of things must come together in order that there be a cause; one man, for example, is not the cause of the motion of a ship, but many; and one stone is not the matter of a house, but many.

In 29. , Aquinas considers briefly a fourth division of causes, the division into simple causes and composite causes. This division has been taken in two different ways.

In the first way, a simple cause is one which is said to be a cause by itself alone, whether a per se cause by itself alone, or a per accidens cause by itself alone. The builder, for example, is the simple per se cause of the house; and the medical doctor is the simple per accidens cause of 16 Avicenna, ” Sufficientia,” II, 8: … simplex est cum opus provenit ex una virtute, ut attrahere et expellere a virtutibus corporalibus. Sed compositum est cuius opus provenit ex multis virtutibus quae sint una in specie, ut multi homines cum movent navem, aut diversam speciem [sc. quae sint diversa in specie], sicut fames quae fit ex virtute activa et sentiente. (Ex. Cod. Paris. Nat. Lat. 6443, fol. 51r). — From Mattingly, op. cit. , p. (38).

the house. A cause is a composite cause when both together are said to be the cause, i.e., both the per se cause and the per accidens cause; as when the buildermedical doctor is said to be the cause of the house, or of health. Or, as when this cold thingpiece of wood is said to be the material cause of the statue; or of the head board of a bed.

The second way of taking this division is a way suggested by Avicenna. A cause is a simple cause, if it is said to be the cause by itself alone, but in the sense of one thing rather than many. There is no need here for many things to come together in order that there be a cause. For example, when a piece of wood suffices as the material cause of a statue, as opposed to the case in which a statue requires, say, wood and bronze and glass and iron, as its multiple material cause. The wood alone is a simple material cause; the wood plus bronze plus glass plus iron is a composite material cause. In these examples, both the simple cause and the composite cause are per se material causes. But both can just as well be per accidens material causes. For example, this hot thing (which is also a piece of wood) is a simple per accidens cause of the statue. And this hot thing (which is also a piece of wood) plus this cold thing (which is also a piece of bronze) plus this very heavy thing (which is also a piece of glass) plus this rusty thing (which is also a piece of iron) is a composite per accidens cause of the statue. Similarly with respect to the other kinds of cause — formal and efficient and final; both the simple cause and the composite cause can be either per se causes or per accidens causes.

Causes in Act and Causes in Potency

30. Item causarum quaedam est actu, quaedam potentia. Causa in actu est quae actu causat rem, sicut aedificator cum aedificat, vel cuprum, cum ex eo est idolum. Causa in potentia est quae, licet non causet rem in actu, potest tamen causare, sicut aedificator dum non aedificat. Et sciendum quod loquendo de Page 86

causis in actu, necessarium est causam et causatum simul esse, ita quod si unum sit et alterum. Si enim sit aedificator in actu, oportet quod aedificet; et si sit aedificatio in actu, oportet quod sit aedificator in actu. Sed hoc non est necessarium in causis, quae sunt solum in potentia.

Further still, some causes are causes in act, others are causes in potency. A cause in act is a cause which is actually causing a thing; a builder, for example, while he is building, or bronze, when the statue has been made out of it. A cause in potency is a cause which, though it is not actually causing a thing, can cause it; the builder, for example, while he is not building. And it should be understood that, speaking of causes in act, it is necessary that the cause and the thing caused exist simultaneously, in such a way that if one exists so does the other. For, if there is a builder in act, he must be building; and if there is building going on in act, there must be a builder in act. But this is not necessary in the case of causes which are causes only in potency.

In 30., Aquinas turns to a brief consideration of a fifth division of causes, the division into causes in act, or actual causes, and causes in potency, or potential causes.

“A cause in act,” he writes, “is a cause which is actually causing a thing.” One might object that this is a very unilluminating way to try to make something clear; or more strongly, that it is an unacceptable way. For it seems to be saying nothing more than that an actually causing cause is an actually causing cause. And this contributes nothing at all to clarification. — But, if one considers this rightly, one can see that sometimes we refer to things as causes whether they are actually performing as causes or not. And it is to this that Aquinas is calling our attention. For example, we call a sculptor a cause of the statue whether he is actually engaged in exercising his causality, i.e., actually wielding hammer and chisel, or not. When he is so engaged, he is said to be a cause in act. When he is not, he is said to be a cause in potency, meaning that he can, or is able to, be so engaged. And so, a cause in act is an actually causing cause; a sculptor sculpting, a Page 87

builder building, a medical doctor doctoring, A cause in potency is a cause which is not, but can be, an actually causing cause.

One can see very readily that effects are properly explained only by their actual causes. Potential causes are unacceptable. To say that this is now an effect of something which can, but is not now causing it, is unacceptable; or at least very misleading. As Aquinas emphasizes, in the case of causes in act, the cause and the effect must exist simultaneously; if one exists so does the other. Sunlight is the actual effect right now of a simultaneously existing, and right now efficiently causing, sun. The statue is the actual effect right now of a simultaneously existing, and right now materially causing, bronze. The motion of a physical thing in motion is the actual effect right now of a simultaneously existing, and right now moving, mover. This quite clearly, one might like to note, is how Aquinas intends his First Way to be understood. The motion of the thing observed to be in motion — which (motion) is the point of departure of the First Way — as well as the moved movers, however many there may be — the existence of which (moved movers) is inferred from the fact of motion — and the Unmoved Mover Itself — the existence of which is the conclusion of the argument — must all of them exist simultaneously. This observed motion is the actual effect right now of a simultaneously existing, and right now moving, number of moved movers in series, and of a simultaneously existing, and right now moving, Unmoved Mover. If there is a mover in act, it must be moving; and if there is moving going on in act, there must be a mover in act. This, however, is not necessary in the case of movers which are movers only in potency.

For a mover in potency is a mover which is not, but can be, an actually moving mover. A mover which is not actually a mover need not, indeed cannot, have an actually, and simultaneously, existing effect. A cause which is not actually a cause can have, so to say, only an effect which is not actually an effect. Or, such a cause cannot have an effect which is actually an effect.

Universal Causes and Singular Causes

31. Sciendum est autem quod causa universalis comparatur causato universali, causa vero singularis comparatur causato singulari; sicut dicimus quod aedificator est causa domus, et hic aedificator huius domus.

Lastly, it should be understood that a universal cause goes with a universal effect, whereas a singular cause goes with a singular effect. We say, for example, that a builder is the cause of a house, and that this builder is the cause of this house.

In 31., Aquinas touches on a sixth division of causes, the division into universal causes and singular causes. A universal cause, he notes, comparatur, “goes with,” a universal effect, and a singular cause with a singular effect. And though he does not take time to make explicit what he means by the word “comparatur,” one can surely take him to have in mind both 1) explanation and 2) definition.

As regards explanation, universal effects are properly explained only by appropriately universal causes, and singular effects by appropriately singular causes. Whereas a builder is the appropriately universal cause which explains the building of a house; this builder is the appropriately singular cause which explains the building of this house. Similarly, whereas wood is the appropriately universal material cause which explains the existence of a statue; this wood is the appropriately singular material cause which explains the existence of this statue. Similarly for final and formal causes. — For more on how to explain effects properly, see above pp. 78–81, the section entitled Semper debemus reducere quaestionem ad primam causam.

As regards definition, a universal cause can be defined as a cause with a universal effect; a singular cause, as a cause with a singular effect. For example, whereas what a builder is, is an efficient cause whose effect is the building of a house; what this builder is, is an efficient cause whose effect is Page 89

the building of this house. Similarly, whereas wood can be defined as a material cause whose effect is a statue; this wood can be defined as a material cause whose effect is this statue. Similarly, for final and formal causes.

Chapter Six—

Sameness and Difference in Matter and Form

In chapter six, Aquinas turns his attention to matter and form, the intrinsic causes of physical things which come to be in substantial change, in order to point out, and make clear what it means to say, that 1) what is numerically the same has a matter and a form which are numerically the same, 2) that things which are specifically the same have a matter and a form which are specifically the same, 3) that things which are generically the same have a matter and a form which are generically the same, and 4) that things which are the same only according to an analogy have a matter and a form which are the same only according to an analogy. Then, in order to make these things clear, he finds it helpful, indeed necessary, to talk about univocal, equivocal and analogical predication.

Things:

The Same in Number, the Same in Species, the Same in Genus, and the Same Only According to an Analogy 32. Sciendum est etiam quod loquendo de principiis intrinsecis, scilicet materia et forma, secundum convenientiam et differentiam principiatorum est convenientia et differentia principiorum. Quaedam enim sunt idem numero sicut Socrates et hic homo, demonstrato Socrate. Quaedam sunt diversa numero, sed idem in specie, sicut Socrates et Plato, qui, licet conveniant in specie humana, differunt tamen numero. Quaedam autem differunt specie, sed sunt idem genere; sicut homo et asinus conveniunt in genere animalis. Quaedam autem sunt diversa in genere, sed sunt idem solum secundum analogiam; sicut substantia et quantitas, quae non conveniunt in aliquo genere, sed conveniunt solum secundum analogiam. Conveniunt enim solum in eo quod est ens; ens autem non est genus, quia non praedicatur univoce, sed analogice.

It should also be understood that, speaking of the intrinsic principles matter and form, there is a sameness and a difference of principles according to the sameness and difference of the things derived from these principles. For some things are

the same in number, like Socrates and this man, Socrates being pointed out. Some things are diverse in number, but the same in species, like Socrates and Plato, who, although they agree in the human species, differ nonetheless in number. Others, differ in species, but are the same in genus; a man and an ass, for example, agree in the genus of animal.

Others, still, are diverse in genus, but are the same only according to an analogy, like substance and quantity, which do not agree in any genus, but only according to an analogy.

For they agree only in being. And being is not a genus, because it is not predicated univocally, but analogically.

In 32., Aquinas begins by observing that the matter and the form of things which are both the same and different in different ways, are both the same and different in correspondingly different ways. Then, he points out a number of ways in which things are both the same and different. Socrates and this man are the same in number, i.e., one when counted, though they are different in name or designation. Being called by the name ”Socrates” is different from being designated by the expression “this man.” Socrates and Plato, however, though the same in species (both of them are human beings), are not the same in number, i.e., not one when counted. They differ in number; they are two when counted. Each has his own designated matter, which is the principle of individuation. A man and an ass, though the same in genus (both of them are animals), are not the same in species. An ass is one kind of animal, a man quite another kind. Each has its own specific difference, which is the principle of the species. Substance and quantity, lastly, are the same only according to an analogy. They are the same neither in number, nor in species, nor in genus. They are the same only in this, that both are beings. But each has its own way of being. Moreover, a way of being is not a genus, cannot be a genus; because unlike a genus, being is not predicated univocally. Being is predicated analogically.

Univocal Predication, Equivocal Predication, and Analogical Predication

33. Ad huius autem intelligentiam sciendum est quod tripliciter aliquid praedicatur de pluribus: univoce, aequivoce et analogice. Univoce praedicatur quod praedicatur secundum idem nomen et secundum eamdem rationem, idest definitionem, sicut animal praedicatur de homine et de asino. Utrumque enim dicitur animal, et utrumque est substantia animata sensibilis, quod est definitio animalis. Aequivoce praedicatur quod praedicatur de aliquibus secundum idem nomen et secundum diversam rationem, sicut canis dicitur de latrabili et de caelesti, quae conveniunt solum in nomine et non in definitione sive significatione; id enim quod significatur per nomen est definitio, sicut dicitur in IV Metaphysicae. 17

Analogice dicitur praedicari quod praedicatur de pluribus, quorum rationes sunt diversae, sed attribuuntur alicui uni eidem, sicut sanum dicitur de corpore animalis et de urina et de potione, sed non ex toto idem significat in omnibus. Dicitur enim de urina ut de signo sanitatis, de corpore ut de subiecto, de potione ut de causa; sed tamen omnes istae rationes attribuuntur uni fini, scilicet sanitati.

For an understanding of this, it should be kept in mind that there are three ways in which something is predicated of many things: univocally, equivocally and analogically. That is predicated univocally which is predicated according to the same word and according to the same meaning, or definition, as “animal” is predicated of man and of ass. For each is said to be an animal, and each is an animated substance capable of sensing, which is the definition of animal. That is predicated equivocally which is predicated of a number of things according to the same word and according to a diverse meaning, as “dog” is said of what is capable of barking and of the heavenly body, which have in common only the word, but not the definition or signification; for that which is signified by a word is the definition, as is said in book four of the Metaphysics. That is said to be predicated analogically which is predicated of many things so that the meaning is different for each, but so that there 17 Aristotle, Metaph. , Bk. IV, ch. 7, 1012 a 22–24.

is an attribution to some one and the same thing, as “healthy” is said of the body of an animal and of urine and of a drink, but does not mean wholly the same thing with respect to all of them. For it is said of urine as of a sign of health, of the body as of the subject of health, and of the drink as of a cause of health. Nonetheless, all of these meanings include an attribution to one end, namely health.

In 33. , Aquinas makes clear what it means to say that a word is predicated analogically, by showing how analogical predication differs from univocal predication and from equivocal predication. In 34. , he continues his consideration of analogical predication. His remarks in 33. and 34. , taken together, are ordered toward explaining his concluding observations in 32. , namely: 1) that there are things which, though different, are nonetheless the same in a special way, i.e., according to an analogy;

2) that in such cases the word, a same word, used to designate this sameness is not predicated univocally, but analogically; 3) that substance and quantity are the same in this special analogical way, and 4) that the word “being” which is used to designate this sameness is not predicated univocally, but analogically.

In most predications, one should note, there are words and meanings and things (referents). The words are predicated of these things with certain intended meanings.

In a univocal predication, a same word is predicated of many different things with a meaning which is wholly the same. For example, the word “animal” is predicated of men and dogs and horses (and of many other things as well) with this same meaning, namely sensing organism; or, the word “organism” is predicated of trees and dogs and men (and of many other things besides) with this same meaning, namely living body. In an equivocal predication, a same word is predicated of many different things, but of each with a meaning which is wholly different. For example, the word “pen” is predicated of this thing with the meaning writing instrument, and of that thing with the meaning enclosure for animals; or, the word “bank,” of this thing with the meaning money saving and lending institution, and of that thing with the meaning the rising ground bordering a

river. In an analogical predication, a same word is predicated of many different things with a meaning which is both the same and different, partly the same and partly different. To explain. There is a first meaning, and a number of posterior meanings. Part of the first meaning is retained as part of each of the posterior meanings. The posterior meanings differ from the first meaning, and from one another as well, by adding a different relation to the retained part of the first meaning. The word

“healthy,” for example, is predicated of many things in this way. Its first meaning is the meaning predicated of things, living organisms, which are appropriate subjects of the bodily disposition which is health. We say that this man is healthy, or that this dog is healthy, and we mean that they have, or are subjects of, the bodily disposition which is health. Then we extend the word “healthy” to other things because these other things have a relation (other than that of being a subject) to the bodily disposition which is health (this disposition is the retained part of the first meaning). Urine, for example, is said to be healthy because it is a sign of the bodily disposition which is health. Food is said to be healthy, because it is preservative of the bodily disposition which is health. Medicine is said to be healthy, because it is restorative of the bodily disposition which is health. The meaning bodily disposition which is health is part of each of the several meanings of the word “healthy.”

The posterior meanings differ from the first meaning, and from one another, by adding a different relation to the retained part of the first meaning, i.e., to bodily disposition which is health; one meaning (said of urine) adds the relation sign of, another (said of food) the relation preservative of, still another (said of medicine) the relation restorative of. And health is the one end, or goal, of which the living organism is the subject, of which the urine is a sign, and which the food preserves, and the medicine restores.

One End, or One Agent, or One Subject

34. Aliquando enim ea quae conveniunt secundum analogiam, idest in proportione vel comparatione vel convenientia, attribuuntur uni fini, sicut patet in praedicto exemplo;

aliquando uni agenti, sicut medicus dicitur et de eo qui operatur per artem et de eo qui operatur sine arte, ut vetula, et etiam de instrumentis, sed per attributionem ad unum agens quod est medicina. Aliquando autem per attributionem ad unum subiectum, sicut ens dicitur de substantia et de quantitate et qualitate et aliis praedicamentis. Non enim ex toto est eadem ratio qua substantia est ens et quantitas et alia; sed omnia dicuntur ens ex eo quod attribuuntur substantiae, quae quidem est subiectum aliorum. Et ideo ens dicitur per prius de substantia et per posterius de aliis; et ideo ens non est genus substantiae et quantitatis, quia nullum genus praedicatur per prius et posterius de suis speciebus. Sed praedicatur analogice. Et hoc est quod diximus, quod substantia et quantitas differunt genere, sed sunt idem secundum analogiam.

Now, sometimes the things which are the same according to an analogy — that is, in a proportion or comparison or agreement — are attributed to one end, as is dear in the example just noted. Sometimes they are attributed to one agent, as “medical” is said both of someone who works by means of his art and of someone who works without the art, as an old experienced woman, and even of instruments; and in each of these cases by an attribution to one agent which is the art of medicine. At other times, they are attributed to one subject, as “being” is said of substance and of quantity and quality and the other predicaments. For that by which substance is a being, on the one hand, and that by which quantity and the others are beings, on the other hand, are not wholly the same. All of these others are said to be beings because of the fact that they are attributed to substance, which of course is the subject of all of them. And so, “being” is said first of all of substance, and posteriorly of the others. And this is why being is not a genus in relation to substance and quantity, i.e., because no genus is

predicated of its species, first of one, and posteriorly of others, and being is predicated just that way, i.e., analogically. And this is what we said above, that substance and quantity differ in genus, but are the same according to an analogy.

In 34. , Aquinas adds to what he had said about analogical predication in 33. , by pointing out that the diverse things, and their diverse relations, which figure in analogical predications are attributed at times to one and the same end, as to health in the example offered in 33. . Health, quite clearly, is the one end desired by the living organism which is the subject of health, the one end of which urine is a sign, the one end which food preserves, and the one end which medicine restores. But, at times they are attributed to one and the same agent, and at times to one and the same subject. — To one and the same agent, as in the case of the word

“medical,” to the one who possesses the art of medicine, i.e., the medical doctor. The word “medical” is predicated per prius of 1) the medical doctor who does his medical work by means of the art he possesses, and per posterius of other things, such as 2) the old woman, perhaps a midwife, who does her medical work without the art which the medical doctor has, but rather by her years of medical experience, and 3) even of the instruments, like a syringe or a stethoscope, which are used by those who are engaged in medical work. — The art of medicine, clearly, is in various ways the cooperating agent, or the cooperating moving cause, which assists nature, the primary agent, in its (nature’s) efforts at doctoring. In one way, in the case of the medical doctor; for he possesses the art. In another way, in the case of the old woman; for she possesses the experience and the knowhow, though without the art, which (experience and knowhow) others have because they have the art. In still another way, in the case of the medical instruments; for they are things which are necessary, or at least helpful, for a better functioning of the art.

At times the diverse things, and their diverse relations, which figure in analogical predications are attributed to one and the same subject, as in the case of the word

“being,” to what is an ultimate existing thing, i.e., to

substance. The word “being” is predicated per prius of 1) substance, which is what has existence in and of itself, and which therefore exists in a most proper sense;

and per posterius of other things, such as 2) quantity, 3) quality, 4) relation, and 5) the other predicaments, all of which have existence only in relation to substance, none in and of themselves, and so exist in a less proper sense.

Matter and Form:

The Same in Number, the Same in Species, the Same in Genus, and the Same Only According to an Analogy 35. Eorum igitur quae sunt idem numero, et forma et materia sunt idem numero, sicut Tulii et Ciceronis. Eorum autem quae sunt idem specie, sed diversa numero, etiam materia et forma non est eadem numero, sed specie, sicut Socratis et Platonis. Et similiter eorum quae sunt idem genere, et principia sunt idem genere; ut anima et corpus asini et equi differunt specie, sed sunt idem genere. Et similiter eorum quae conveniunt secundum analogiam tantum, principia sunt eadem secundum analogiam tantum, sive proportionem.

Materia enim et forma et privatio, sive potentia et actus, sunt principia substantiae et aliorum generum. Tamen materia substantiae et quantitatis, et similiter forma et privatio, differunt genere, sed conveniunt solum secundum proportionem in hoc quod, sicut se habet materia substantiae ad substantiam in ratione materiae, ita se habet materia quantitatis ad quantitatem. Sicut tamen substantia est causa caeterorum, ita principia substantiae sunt principia omnium aliorum.

And so, the form and the matter of what is numerically the same, are also numerically the same, for example of Tullius and of Cicero. The matter and the form of things which are the same in species, but diverse in number, for example the matter and the form of Socrates and of Plato, are likewise not the same in number, but only in species. Similarly, the principles of things which are the same in genus, are themselves the same in genus; for example, the soul and the body of an ass and of a horse differ in species, but are the same in genus. Similarly, again, the principles of things which are the same only according to an analogy, are the same only according to an analogy, or a Page 98

proportion. For, matter and form and privation, and potency and act as well, are principles of substance and of the other genera. Nonetheless, the matter of substance and of quantity, and similarly the form and the privation, differ in genus but are the same only according to a proportion, which amounts to this, that just as the matter of substance is related to substance as its matter, so too is the matter of quantity related to quantity. Just as substance is the cause of the others, so too the principles of substance are the principles of all the others.

In 35. , Aquinas takes up the main point of chapter six, namely that the matter and the form of things which are both the same and different in different ways, are both the same and different in correspondingly different ways. He begins with sameness in number, then moves to sameness in species, then to sameness in genus, and lastly to sameness according to an analogy only.

Tullius and Cicero are one and the same individual, one and the same in number or when counted, though they are different in name. That is, being called by the name

“Tullius” is different from being called by the name “Cicero,” though both names designate one and the same individual. The form and the matter of Tullius and of Cicero, who are one and the same in number, are one and the same in number. The soul and the body of this man are this soul and this body.

What is the point of this? one may ask. Is its point to note that this man is this man because his body is this body and his soul is this soul? Or, is its point to note that this body is this body and that this soul is this soul, because they are the body and the soul of this man? Does the numerical sameness of the matter and of the form cause, and by causing explain, the numerical sameness of the individual? Or, does the numerical sameness of the individual cause, and by causing explain, the numerical sameness of the matter and the form?

A not unreasonable suggestion is the following, that Aquinas’ point is twofold. 1) To observe that there is a correspondence between the sameness of the matter and form, on the one hand, and the sameness of the things made out of matter and form, on the other hand; so that if the thing is numerically the same, so are its matter and its form; and if the matter and the form are numerically the same, so is the thing; and similarly for sameness in species, in genus, and according to an analogy only. 2) To observe, in accord with the underlying task of this short work as a whole (which is an attempt to become clear on the principles of natural things) that matters and forms of different sorts are the principles of natural things of different sorts; and not vice versa, i.e., not that things of different sorts are the principles of matters and forms of different sorts. Matter and form, and privation as well, are the principles of natural things, matter and form being principles which are also causes, privation being a principle which is not also a cause. Principles which are causes account for the existence of things, whereas principles which are not causes do not.

Matter and form account for existence because they are intrinsic components of the makeup, i.e., ingredients of the essence, of a natural substance; privation is not.

Moreover, universal causes account for the existence of universal effects, less universal causes account for the existence of less universal effects, and individual causes account for the existence of individual effects. Thus, generic matter and form account for the existence of things which are the same in genus, e.g., body and soul account for the existence of an ass and of a horse; specific matter and form account for the existence of things which are the same in species, e.g., human body and human soul account for the existence of Plato and of Socrates; and individual matter and form account for the existence of what is the same in number, i.e., the individual, e.g., my body and my soul account for my existence. Lastly, analogical matter and form account for the existence of things which are the same only according to an analogy, e.g., the matter and the form of substance account, in one way (i.e., as intrinsic components), for the existence of the substance itself, but also, and in other ways (but never as intrinsic components), for the existence

of all the accidents of the substance as well. Some accidents are caused by the form alone of the substance (as by an efficient cause, and as received by an extrinsic matter, or subject), e.g., the human intellect. Some are caused by the form and the matter of the substance together (as by an efficient cause, and as received by an extrinsic matter, or subject), e.g., the powers of sensation. No accidents, however, are caused by the matter alone of the substance (i.e., not as by an efficient cause;

though matter, as ultimate subject, is what accounts for the receptivity of the substance, as a whole composed of matter and form, with respect to its material accidents); for matter, of itself, is just potency without any actuality at all.

PART TWO—

DE MIXTIONE ELEMENTORUM

The Question

How Do Elements Remain in the Physical Things Which Are Made Up Out of Them?

1. Dubium apud multos esse solet quomodo elementa sint in mixto.

There is a continuing uncertainty among many as regards how elements are in a mixed body.

The question being considered in this brief work, as Aquinas indicates in 1., is the question: how are elements in a mixed body?

And, this prompts one to ask: what exactly is this question asking? It is clear that even the beginnings of an answer to the immediately preceding question require, in turn, some sort of answer to further questions, at least the following: what is an element? and, what is a mixed body?

As regards the first question, what is an element?, it should be pointed out, to begin with, that the context here is the physical world. So that, the elements being considered are elements of things in the physical world. — An element, generally described, as Aquinas understands it, is that (whatever) out of which something (whatever) is made, as out of a primary constituent, which remains in that something, and which is indivisible in kind. — An element of things in the physical world, as Aquinas understands it, is a

simple body, a simple physical thing, out of which a complex body, a complex physical thing, is made, as out of a primary constituent, i.e., a constituent which itself has no prior bodily constituents. An element remains in some way in the complex body (exactly how it remains, is the question of this brief work). An element is indivisible in kind, i.e., it cannot be broken down so as to yield parts which are different in kind from its own kind. Moreover, an element can exist separately, i.e., not as a constituent of a complex body, both before and after having been such a constituent. Elements can act upon, and be acted upon by, one another. They become constituents of a complex body only after they have been altered by one another, though not beyond retrievability.

As regards the second question, what is a mixed body?, it should be noted simply that a mixed body is a physical thing which is made up out of elements; a mixed body is what was called a complex body in the immediately preceding paragraph.

Though Aquinas thought, given his times, that water was one of the four elements, the other three being earth, air and fire — an idea going back to ancient Greece —

today we would say that water cannot be an element. It is, rather, a mixed body; for, unlike an element, it is made up out of prior constituents, i.e., out of hydrogen and oxygen. Now, what about hydrogen and oxygen? Would they count as elements? Perhaps not. For, though both remain in water in some way; though both can exist separately, i.e, not as constituents of water, both before and after being such constituents; though both can act upon, and be acted upon by, one another; though both have been altered by one another, but not beyond retrievability, in order to become constituents of water; — it does not seem to be the case that they are primary constituents. For they, in turn, are made up out of prior constituents, e.g., protons and electrons. Nor does it seem to be the case that they are indivisible in kind, for the constituents of oxygen, e.g., electrons and protons,

are other in kind than oxygen, and those of hydrogen, similarly, are other in kind than hydrogen. Shall we say, then, that protons and electrons are the elements of mixed bodies; or that ingredients which are more simple still, are the elements of mixed bodies? Quarks, perhaps? But, can protons, electrons and quarks exist separately, i.e., not as constituents of mixed bodies, both before and after having been such constituents?

A First Answer—

The Elements Remain with Their Substantial Forms, but Their Active and Passive Qualities Have Been Changed into Some Sort of Mean

2. Videtur autem quibusdam quod, qualitatibus activis et passivis elementorum ad medium aliqualiter reductis per alterationem, formae substantiales elementorum maneant. Si enim formae substantiales non remaneant, videbitur esse corruptio quaedam elementorum, et non mixtio.

To some, it seems that, though the active and passive qualities of the elements are changed by alteration into some sort of mean, the substantial forms of the elements remain. For, if the substantial forms do not remain, there would seem to be a corruption of the elements, and not a mixing of them.

3. Rursus, si forma substantialis corporis mixti sit actus materiae, non praesuppositis formis simplicium corporum, tunc simplicia corpora amittent elementorum rationem. Est enim elementum ex quo componitur aliquid primo, et est in eo, et est indivisibile secundum speciem. Sublatis enim formis substantialibus, non sic ex simplicibus corporibus corpus mixtum componetur, quod in eo remaneant.

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