Chapter 3: Souls

3

Souls

Form as a Principle of Life, Kinds of Soul, and Grades of Immateriality

Soul as a Topic for Natural Science

If Thomas’s concept of nature is strange to us, his concept of soul is, if anything, even stranger. Here, for example, is Oxford’s first (and only relevant) online definition of soul: “the spiritual or immaterial part of a human being or animal, regarded as immortal.”135 With that in mind, look at how Thomas begins his treatment of the human soul in the Summa theologiae.136 The first thing he asks is whether a soul is a body. Does he not know what the word means?

Our own first question about soul, I suppose, would be whether there even is any such thing. Thomas takes soul entirely for granted. You may say it is because he is a Christian theologian. But then you must explain why, earlier in the Summa, and certainly speaking as theologian, he did ask whether there is any such thing as a God.137 You must also explain how here, after arguing that a soul is in fact not a body, he can go on to ask, in effect, whether or not a human soul is spiritual.138 That too, Oxford says, is part of the word’s very meaning. Then, after answering this question affirmatively, Thomas asks whether the souls of beasts are spiritual too. He says no; but he is taking it quite for granted that there are such things as beast-souls. And three articles later he asks whether or not the human soul is immortal.

Most of Thomas’s contemporaries would not have found any of the above strange. As mentioned in the first chapter, however, another position of his regarding the soul was indeed problematic for many of them, and it too is hard to square with our usual conception.139 On his view, a soul is not a body, but it is quite thoroughly of a body. It does not have matter in it, but it is immediately united to matter. It is a body’s one and only substantial form. It is thus the very nature of a certain bodily substance, in the strictest sense of the word nature. It is something quite physical. Even the human soul is so—despite its being spiritual and its making us be in the image of God.

Now, Thomas would surely push back against the word despite in the previous sentence. The spiritual soul’s being the body’s substantial form is the very thing that accounts for those uniquely human aspects of the image of God that we noted earlier.140 That man is from man, as God is from God, rests on the soul’s function as nature and as principle of generation; and that the soul is whole in the whole body and whole in every part, as God is in the world, rests directly on the soul’s function as substantial form. But Thomas is insisting that these are not, as it were, optional functions of the human soul. They flow from its very essence. The human soul is not really an angel that happens to have assumed a body. It is not even in the same genus as angels. It really is a soul, that is, an anima, and it is “in the genus of animals.” Of course it is not an animal in its own right. It is in that genus “as a formal principle.”141 But this is exactly how the souls of beasts are in that genus.

If nothing else, it should be clear that, for Thomas, the word soul does not refer to just one kind of thing. Souls come in several different kinds. If we want to make any sense of his conception, then despite the special interest of the human kind, we cannot treat it alone. In fact we must broaden our scope beyond the genus of animals. We must include plants. I hope that eventually it will be clear why Thomas sees no tension between being a substantial form and being spiritual. But first we must get clear about the soul’s being a substantial form.

The Substantial Form of an Organism

Let us go back to that first Summa article, on whether the soul is a body. Thomas begins his answer by telling us what the word means for him. Let us take it as given, he says, that the word soul means “the first principle of life in the living things around us.” If we use his word, anima, the point may be clearer. Anima is what makes the difference between the animate and the inanimate.142 Since the difference between them is life, anima means the first principle of life in a living thing.

To say this, however, is to leave wide open the question of what an anima consists in. And in fact, as Aristotle reports, there were thinkers who held that it is some kind of body or other: fire, air (breath), highly mobile atoms, etc. But precisely because the mere word says so little about the soul’s constitution, it leaves little or no doubt about its existence. One could doubt its existence only if one doubted the distinction between animate and inanimate things. Thomas sees no reason to doubt that.

His next step is to grant that a body can be some sort of principle of life. Most animal life, for example, depends on heart, blood, brain, and so on. Today some might say that the principle of life generally is DNA. But Thomas then argues that no body can be the very first inner principle of life (remember that he put first in the word’s very definition). For any such body will need an inner principle of its own. Why? Because a body’s being alive, or a principle of life, means more than just being a body. It means being a body of a certain type or quality, being such a body (a heart, a brain, an animal). What is the root, within it, of its being such? The fundamental answer cannot be yet another body. That too would be such a body, and the question would still stand.

At this point Thomas introduces the word act, actus. We are talking about what makes a body be such—be alive—in act. The term act is especially suitable in this context, because the very notion of life is tied to activity. In the first place, living things are natural things, and as we have seen, all natural things tend to move and act in some way or other. But living things are especially active. They somehow move themselves or engage themselves in their activity, as its very agents. We judge that a living thing has died when it stops doing that. Living things are more self-sufficient for their activity than non-living things are.143

A soul, then, is not a vital activity, but it is the act underlying such activity. Thomas likens it to heat. Heat is a principle by which a body performs the activity of heating. It is not a body, but an act of that body. Thomas thought heat was a sort of form. Nowadays that view is rejected. But no one says that heat is body. It is some kind of energy in a body. And that is at least quite close to what Thomas is saying about it here—and about soul as well.

In effect, Thomas is simply spelling out Aristotle’s reasoning, at the start of Book II of De anima, for the thesis that a soul is not a body. Of natural bodies, Aristotle says, some have life and some do not. So a body that has life is such a body or a body of a certain type; hence a soul cannot be a body. Rather, a body is its subject or matter, and it is a form and an act.144

Now it should be clear why Thomas can still ask whether the human soul is spiritual. He is not already saying that it is so, any more than he is saying that heat is so. In fact, here he is saying even less than Aristotle does in that place. Aristotle says a soul is “substance as form,” substantial form. Thomas has not yet said that; but he will. He fully endorses Aristotle’s general definition of soul: “substance, as form, of a natural body having life potentially.”

A Principle of Activity and of Substantial Unity

By this last phrase, “having life potentially,” Aristotle means having capacity for vital activity. In this passage, he defines life simply as self-nutrition, growth, and withering. Later he also identifies other kinds of vital activity. But these three, along with reproduction, are the kinds that all living bodies have and that coincide with their being alive at all.145

However, Aristotle does not always identify life with vital activity. He also calls life the very being (einai—Thomas’s esse) of a living thing. He appeals to this meaning to confirm the notion of soul as a substantial form. Substantial form causes a thing to be (as the order of the letters causes ba to be); and soul causes a living thing to live; and for a living thing, to live is to be; and so soul is a substantial form.146 Thomas says that life means both vital activity and the being of a living thing, but the latter is its primary meaning.

Later we will look at the relation between being and form more closely. These are highly abstract notions, and it will help to have on hand this concrete example: life as being, and soul as form. But the distinction between being and activity is also important as regards the nature of soul itself. Actual being, or being alive, follows immediately and inseparably upon the possession of soul. But not all vital activity follows upon it in that way. Whatever has a soul is actually alive, not just potentially so; but it is not always performing all the kinds of vital activity that it is capable of. This seems inevitable, given that it is a self-mover. Some of its activities are brought about by way of others, and at least some of these are motions and so take time to complete. Normally, for instance, a new organism has to grow for a while before it is ready to reproduce. With respect to the vital activities, then, what follows immediately upon the possession of soul is only a determinate potential or capacity for them. Aristotle in fact stresses that the phrase “having life potentially” in his definition does not refer to what does not yet have soul, as though soul were the act of that potential; the act of that potential is vital activity. The phrase, he says, refers to what does have soul and is thereby both actually alive and in potency to vital activity. In other words, soul is what he calls a “first act.” Vital activity is a further act, the potential for which accompanies that first act.147

Another way to see the distinction between being alive and vital activity is to consider that an individual living thing’s vital activities are of many kinds, but the thing itself is one thing, with one being and one life. And the form, the soul, is first of all the very principle of its unity. It makes the living body be one body. So it is not added to the body, but rather is constitutive of it. What it is added to is matter, which is only potency for a body. To be sure, both Aristotle and Thomas often follow the common practice of speaking of soul and body as the components of a living thing. But Thomas justifies this practice by saying that although the same form that makes the thing a substance and a body also makes it be alive, we can consider being a body as a merely imperfect effect of this form, one that it has in common with forms that are not souls, and as merely potential or material relative to the effect of being alive, which is proper to it as soul.148 Our habit of speaking of soul and body, then, merely reflects our way of getting at the natures of things, which involves comparison and contrast. This procedure gives rise to conceptual or logical distinctions that do not always line up exactly with the real makeup of things.149 They are not therefore bad or false, but they must not be confused with real distinctions, such as the distinction between form and matter.

However, we can still ask whether it is really true that the form proper to a living thing is a substantial form. This amounts to asking whether the thing itself is really a substance. Right after defining soul as the first act of a natural body having life potentially, Aristotle observes that such a body is organic. This means that it has bodily parts serving as tools or instruments (organa) of vital activities. The parts have very diverse qualities and operative tendencies. Might the living thing not really be just a combination of bodies of different natures, like a machine?

The question may sound rather modern, but Aristotle faced it squarely.150 He tells us that Empedocles explained the downward growth of plant-roots by their containing earth, which naturally tends in that direction, and the upward growth of other parts of the plant by their containing fire. Aristotle retorts: there must at least be something that holds the earth and fire together so that the plant is not torn apart. And what is more, the movements involved in the growth of a plant (or an animal) are intrinsically regulated and limited, toward a fairly definite size and shape and disposition. Growth is not a combination of unrelated motions, but a distinct kind of motion in its own right. Qualities of elementary bodies may very well be contributing to it somehow.151 But its primary source is a principle proper to the living thing, a principle running through all the thing’s parts. Its parts are essentially just that, parts, defined by their function in and order to the whole. They do not exist outside the whole, at least not in a stable way; it is unnatural for them. The thing is a single substance, with a nature and a form proper to it. There is no form or set of forms in it that is more basic than the form by which it is alive, its soul.152 Our machines imitate living things. It is a kind of anthropomorphism to suppose that living things are constituted in the manner of machines.

Thomas’s notion of soul and body, then, is hardly a specimen of “Greek dualism.” Nor is Aristotle’s. It makes no sense, Aristotle says, to ask whether soul and body are one, any more than to ask whether wax and the shape impressed in it are one. Matter and form are potency and act, and what is one in the primary sense is what is one in act.153 Again, instead of saying that a thing is composed of matter and form, we would do better to say that its matter is composed—unified—according to its form. An organism is not two kinds of things somehow joined. It is one kind, now in potency, now in act. The whole point, we might almost say, of Aristotle’s hylomorphism—of which the doctrine of soul is the very centerpiece—is to uphold the substantial unity of natural bodies.154 And substantial unity is the primary type of unity.155

Grades of Substantial Form and Kinds of Soul

We might wonder why, if soul is nothing but a particular kind of substantial form, it has this special name, soul. Thomas would surely answer that not all substantial forms are equal. Souls are more perfect than the forms of inanimate bodies. They are more perfect precisely as substantial forms, that is, as principles of being, unity, and activity. With respect to activity, their greater perfection is shown by the living thing’s self-movement or self-engagement. With respect to unity, it is shown by the generally greater definiteness and distinctness of living bodies, and also by the very diversity of the organism’s parts; to effect substantial unity in such diversity requires more, not less, unitive energy. It is also shown by the living thing’s aptitude for producing and repairing its own parts and organs and thereby preserving the thing’s integrity.156 With respect to being itself, their perfection is shown by the nutritive and reproductive operations, through which the organism preserves both its own being and that of its kind. Indeed, it is especially in living things that the nature of the kind, as founded on the form, is seen to function as its own promoter and its own end.157 The causal roles that form is apt to exercise—formal, efficient, and final—are on full display.158

Plants have only nutrition, growth and withering, and reproduction. Animals of course also have sensation and (usually) movement from place to place, and, in the case of man, intellect or understanding. Do animals then have a plant-like soul together with one or more others? Thomas says no, each is one substance with just one form. But those with different and ampler sets of vital activities have different, more perfect kinds of soul.159 Thomas takes on board an ingenious comparison proposed by Aristotle.160 The different kinds of soul are like different rectilinear figures: triangle, quadrilateral, pentagon. Each is a single figure or form, but every successive one contains “in potency” whatever is in the prior, plus more. It has more vital powers. The powers that even plants have are called vegetative powers. Animals also have sensation. But the vegetative powers of an animal are obviously very different from those of a plant. They are reconfigured and integrated with the animal’s other powers. Similarly, man’s vegetative and sensitive powers differ from those of plants and beasts. They are integrated with reason.

As mentioned in the first chapter, Thomas’s insistence on man’s having just one soul troubled the theologians, who saw it as a threat to the spirituality and immortality of the properly human, rational soul. After all, the idea of sub-rational powers existing apart from the body makes little sense. Can souls metabolize, or walk, or thirst? Thomas, however, simply distinguishes between the soul just in itself, or in its essence, which is to be a certain form and act, and its powers. If the human soul can exist apart from the body, then it can also exist without those powers that are seated in bodily organs. It can do so even though it remains a principle of such powers, just as it remains a form apt to inform an organism.161

The question of the human soul’s unity also bears on current issues. For instance, does the irreversible cessation of cognitive functions imply that a person is dead? Does it imply the loss of the soul itself, or only of certain organs or powers? On Thomas’s account of the soul, death cannot be without the loss of the body’s integrative vegetative functions.162

The Distinction and Distribution of Powers of Soul

Different kinds of soul bring different sets of vital powers, but not every distinct power implies a distinct kind of soul. And although the living thing need not always be exercising its vital powers, and some powers can be exercised independently of others, the possibility of separate or independent exercise is not the basis upon which Thomas distinguishes the powers. In fact, he considers the exercise of certain powers inseparable from that of certain others, and yet the powers remain distinct. For instance, sense-appetite cannot be exercised without sensation, nor (in this life) intellect without imagination, nor will without intellect; and none of the properly animal or human powers can function if the vegetative powers are inactive. But the proper basis upon which Thomas distinguishes the powers is the nature of their activities. These, in turn, are distinguished by what he calls their proper objects.

This is a complicated topic, and a full treatment would require a book of its own. Here I would simply stress that the word object, in this context, is not synonymous with thing. A thing may very well be an object, but in calling it an object, we are seeing it as related to an activity or a power—as something with which the power or activity somehow engages. The idea is reflected in the grammatical notion of the object of a verb. Thus the objects of many different activities may be one and the same thing. Charlie pitched the ball, Jimmy hit the ball, Tommy caught the ball, etc. Conversely, a single kind of activity or power can engage with a variety of things or have many things for its object. However, if it is really a single kind, then there is always some single feature of the things, by virtue of which it engages with them. There is something that constitutes the thing’s interface with the power. This is what Thomas means by the activity’s or the power’s proper object. For instance, eyesight can bear on many different things, but it bears on them by virtue of their having color (or more precisely, illuminated color). Color is the proper object of eyesight. And if different powers can engage with the same thing, it is because the thing has different features, corresponding to them. Sight grasps a thing according to its color. Intellect may grasp the same thing according to the feature that engages intellect or functions as its proper object, namely what the thing is.163 To understand a thing is to know what it is; the better that is known, the better the thing is understood.

Thomas’s broadest distinction of vital powers is into five broad classes or genera. The distinction proceeds according to two criteria.164 The first, which yields a threefold set, is the range or the extension of the powers’ proper objects. The most limited are the objects of the vegetative powers, those that even plants have: nutrition, growth, reproduction. The objects of these powers are always within the organism itself: its own conservation through the assimilation of nutrients, its due size and shape, its offspring (which at least begins within the organism). Then there are powers whose objects belong also to other sensible bodies. Finally, there are powers whose objects extend even beyond bodily things to absolutely all beings.

Thomas does not give these last two groups, those with broader objects, names of their own. Instead he subdivides each of them into two and names the four results. It is here that he uses the other criterion of distinction. It applies only to these broader powers, because it supposes the possibility of bearing on things entirely outside the organism. The criterion is the direction of the relation that the power establishes between the soul and the things that have the power’s object. First of all, there are powers by which the soul can, as it were, take things into itself—not in their own being, of course, but according to some likeness of them. These are the cognitive powers, sensitive (bearing on physical bodies) and intellectual (bearing on all beings). Then there are powers by which the soul, having the cognitive likenesses of things, can incline or tend toward them according to their own being. These are of two sorts. The primary sort are the appetitive powers, by which the soul relates to things as ends that it is apt to desire and cling to.165 And then there are the motor powers, which are instrumental to the appetites, enabling the animal to move from place to place in pursuit of the end: power to walk, or swim, or fly, and so forth.

It is important not to think of the powers as little agents inside the organism. Properly speaking, what performs the activities pertaining to a given power is not the power itself, but the power’s subject—the organism that has the power. The power is only a principle in virtue of which the subject acts. Thomas will sometimes speak of the senses sensing, the intellect understanding, and so forth, but this is mere economy of language. On the other hand, organisms do have parts, which are distinguished precisely by their powers, and Thomas judges that it is indeed proper, in a secondary way, to say that the part performs the activity in question. For instance, it is not proper to say that hearing itself hears; and what is most proper is to say that the animal hears with its ear, by virtue of its hearing; but, assuming that hearing is seated in the ear, it is not improper to say that the ear itself hears. This fits with the fact that for Thomas, as for Aristotle, the parts of substances—roots, ears, brains—can be considered substances too, albeit partial ones.166 They may not be able to exist separately from the whole, or to operate independently of other parts, but they are still partial subjects of the living thing’s activity, just as they are partial subjects of its life and its being.

The aforementioned powers are distributed among living things in such a way as to constitute four “modes of life.” The simplest mode is occupied by plants, which have only vegetative powers. Then there are animals (relatively few) such as oysters, that have sensation and appetite but no motor powers. Then come the animals that also have motor powers. The most complex mode, of course, is man’s, who also has intellect and will. Appetitive powers do not constitute a mode of their own, since everything that has cognition also has appetite.

The Elevation of Soul above Matter: Metabolism and Reproduction

But let us go back to the various kinds of soul. Thomas ranks them in more than one way. The most obvious way is according to the number of powers that they bring with them. That is how the four modes of life are ranked. But it should also be clear that the powers can be ranked among themselves, according to the extension of their objects. The vegetative powers are more limited than, and as such are less perfect than, the sensitive, and the sensitive are more limited and so less perfect than the intellectual. (In this ranking, the sense-appetite and the motor power can be grouped with the senses, and the will with the intellectual powers.) Now, Thomas takes this threefold ranking of powers to reflect a threefold ranking in the essential perfection of souls themselves; that is, their perfection as first acts of natural bodies. Putting it more concretely, he holds that the greater breadth of a power’s object indicates an activity that “rises above” mere bodily nature to a higher degree. And this in turn indicates a soul that “exceeds” or stands out from bodily matter to a higher degree.167 Every form, Thomas says, considered as act, stands far from matter, which is a being merely in potency.168 Standing out from matter pertains to act as act and form as form. And so a form that stands out more from matter is a more perfect act, and a more perfect form.

This is not an easy topic. But we can hardly set it aside. It will prove crucial for Thomas’s conception of spiritual reality, and of reality simply. I shall approach it quite gradually.

First, let us see briefly how even the vegetative soul stands out from matter more than non-vital forms do. Earlier we remarked on how, even at the vegetative level, soul is a more perfect principle of being, unity, and activity than other substantial forms are. Thomas traces this to a greater degree of self-sufficiency vis-à-vis matter. Obviously it is not that a plant’s soul can exist without matter; that would be absurd. Nor is it that a plant has features or activities that are not somehow conditioned by matter. But two phenomena show a certain transcendence of matter. One is metabolism. By it, an organism’s matter undergoes constant changeover, and yet the organism retains its identity.169 This is because the form through which it lives and exists continues. So long as it has the same life and existence, it is the same being. The form always needs some portion of matter or other, but it needs the portion that it is in now only for a time, and it is what guides the renewal process.170

The other phenomenon is reproduction. The soul transmits something of itself, its own ratio or formula, to other portions of matter.171 Of course a non-living kind may have many instances, but they are seldom self-multiplying. Non-living things are not born, properly speaking, and do not have offspring; rocks do not reproduce. Vital form, soul, is fully self-communicating and self-multiplying, and in this way it stands out more than other forms from the matter in which it inheres. Thomas says the reproductive power in a way approaches the dignity of the sensitive soul, inasmuch as its operation within the living thing extends to exterior things as well.172

The Elevation of Soul above Matter: Cognitive Likeness

But the sensitive soul, he goes on to say, regards exterior things in a more excellent way. And this way, he holds, involves an even greater elevation above matter. The intellectual soul’s excellence and elevation are greater still. To some extent, however, the two can be treated together, under the general heading of cognition. In what follows I shall first consider how Thomas thinks cognition generally involves a more perfect soul and one more elevated above matter. This will take several steps. Then I shall discuss the superiority of intellect over sense. Along the way, key elements of his philosophy of cognition and knowledge should emerge.

As we saw, cognitive operation extends to exterior things by virtue of likenesses of them received in the operation’s subject. Right here, Thomas argues, we see the greater perfection of the cognitive soul. It is, as it were, so big as to contain the forms of other things too.173 At the start of the Summa’s first article on knowledge (God’s), we read: “Cognizers differ from non-cognizers in this, that the latter have none but their own form, whereas a cognizer is apt to have the form of some other thing as well; for the cognitive likeness of the thing cognized is in the cognizer. Hence it is clear that the nature of a non-cognizer is more contracted and limited, while the nature of cognizers has a greater amplitude and extension.”174

Cognoscens is the Latin word that I have rendered with the admittedly ugly cognizer. It is supposed to cover both what has only sensation and what has intellect. Perhaps knower would do, but I prefer to reserve know and its cognates for Thomas’s scire (whence scientia, which, like knowledge, is broader than what is usually meant now by science, yet narrower than cognition). As for cognitive likeness, the original term is species, which in Latin is ambiguous. It can mean what it does in English—a kind of thing (especially living thing)—but it can also mean an aspect, a look, a likeness, and other things as well. But in the context of discussions of cognition, Thomas uses it to refer to that likeness of a thing which a cognitive power enables the cognizer to take into itself. In the above passage he presents it as a type or a mode of form. This is simply because likeness is agreement in form.175 Not all likeness, however, is in the cognitive mode. In a moment we will consider what Thomas thinks is special (pun intended) about this mode.

Why does a cognizer have to have a likeness of the thing cognized? The reason is simple: the activity of cognizing, even when it bears upon an external thing, is in the cognizer. If the thing itself is not in the cognizer, as obviously it often is not, then at least its likeness or its form must be so. The form need not be the thing’s substantial form; Thomas thinks only intellect can assimilate that. But the senses can assimilate accidental forms of various sorts.

Now, as Aristotle presents them, most of his predecessors held that what cognizes has a likeness of what is cognized.176 He agrees. Nearly all of them, however, were thinking that “it takes one to know one”—that the cognizer’s own nature was actually like that of the thing cognized. Aristotle finds this untenable. If it were true, he says, then the cognizer should always be actually cognizing the thing. It should also always be cognizing itself, since it is like itself. And indeed all things, being like themselves and like others, should be cognizing. So he concludes that what the cognizer’s nature has is not an actual likeness of what is cognized, but only potency for such likeness. The cognitive powers are just such potencies. But they are actualized—actual cognition occurs—only through the action of the things themselves. The things must impress their likenesses upon the cognizer, according to its potency to receive them.

This, however, is by no means Aristotle’s whole account of cognition. It hardly could be, since it applies to any sort of change (on his account of change). When fire heats something, it impresses a likeness of itself on what has potency to receive it. Yet being heated by fire is by no means the same thing as perceiving or knowing fire. What is the difference? Thomas’s passage indicated it, very briefly. The cognizer, he said, not only has its own form, but also is apt to have the form of some other thing. He is not saying that the cognizer is apt to lose its own form and take on one like that of another thing. That is what happens when cool water is heated by fire. It loses its coolness and takes on heat. And the heat that it takes on is its own, not the fire’s; it is only like the fire’s. By contrast, the form which the cognizer is apt to take on is not just like a form of the thing cognized. It also is a form of the thing cognized. When you put your cold hand in warm water, you feel the water’s warmth well before your hand becomes equally warm. This means that your hand already has a likeness of the water’s warmth—a likeness that is not your hand’s warmth, because your hand is not yet warm. The likeness of the water’s warmth is a form in your hand, but it is also somehow the water’s form. It must be, if by it, what you feel the warmth of is the water, not your hand. Of course, eventually your hand does take on its own warmth. But in many other cases of sensation, you never do take on a similar form of your own. With your blue eyes you are seeing the black and white page. Nothing in you thereby is, or is even in the process of becoming, black and white. The blue in your eyes is only the blue of your eyes. But the forms of black and white in them are also the page’s forms. They are the page’s inasmuch as by them, the page itself is being seen.

So when Thomas says that the nature of cognizers has a greater amplitude and extension than that of non-cognizers, the notions of amplitude and extension go together. After all, anything that has a substantial nature, whether or not it has cognition, can also take on additional, accidental forms. But the nature of what has cognition is more ample, because it can take on additional forms that, while being in it, are also of other things. In other words, the forms that it can take on are themselves ampler forms, because they extend to other things. They do so in this sense: the form by which the cognizer actually knows, and the form by which the thing cognized is actually cognized, is one and the same form. I mean one and the same individual form. It is in the cognizer, but it is not contracted or confined to him.

Clearly it is crucial not to think that the cognitive likeness itself is what is being cognized.177 The likeness is nothing but the formal principle, in the cognizer, by which it (he/she) cognizes the thing. Thomas’s very point of departure in the treatment of cognition is that, through it, the soul’s activity extends to other things. The soul, or the animal, is not perceiving or knowing itself and then somehow taking itself as a representation of other things. Quite the contrary: what is first cognized is something else, and then that act of cognizing makes the cognizer cognizable to itself (himself/herself), as cognizing something else. This is what nowadays is called consciousness. For Aristotle and Thomas, it exists at both the sensitive and the intellectual levels.178 But it is not the defining or most characteristic feature of cognition.

The Elevation of the Cognitive Soul: One Act of Diverse Potencies

This may all sound very odd. From the standpoint of Aristotelian natural philosophy, the oddness can be somewhat mitigated, if we recall an observation of Aristotle’s about physical activity: the activity of the agent, its action, and the activity of what is acted upon, its passion, are one and the same motion, taking place in what is acted upon.179 A fire’s action of heating, for example, is not a process that the fire itself undergoes. The process is in the thing heated. Yet it is still of the fire too, inasmuch as it is still the fire’s action. Similarly, a thing that is cognized impresses its likeness on the cognizer, and although the impressing is the action of the thing, it takes place in the cognizer. In short, heating and being heated are one and the same activity, and so are the cognizer’s cognizing the thing and the thing’s being cognized.180

However, there are also large differences. The form by which the fire heats is in the fire and not in the thing heated. Once the thing heated becomes as hot as the fire, or has an equal form of heat, the heating stops.181 And the form in the thing heated is only its form, not the fire’s too; what the thing does because of that form does not regard the fire at all. By contrast, the activity of cognition takes place precisely as a result of the cognizer’s having the likeness of the thing cognized. The impressing of the likeness upon the cognizer is only the origin of this activity, not the activity itself. You are seeing the banana’s yellow because you have already received the form of its yellow. And whereas the form by which the fire heats is only a form of the fire and not of the thing being heated, the very form by which the cognizer cognizes is a form of the thing cognized too. Cognizer in act and cognized in act are one and the same.182 That is, one and the same form is the act of both.

What are not the same are the forms by which cognizer and cognized are in potency to this activity.183 The cognizer’s potency is its cognitive power: touch, eyesight, intellect, etc. The cognized’s potency is simply the form inhering it, whose likeness it is apt to impress on the cognizer: its heat, its color, its substantial nature, etc. Color and eyesight are very different things. Indeed the chief contrast that Thomas wants to draw in the above passage is right here. He is pointing mainly to the amplitude and the extension of cognitive powers and of the natures that underlie them, as compared with non-cognitive forms and natures. The passage thus goes on: “For this reason the Philosopher says in De anima III [8, 431b21] that the soul is in a way all things.” He is talking about the soul that has sensation and intellect. It is in a way all things insofar as it has potency for the cognitive likenesses or forms of all things.

How exactly is this to be all the things themselves? Of course, it is to be them only in potency, but that is not the main point. Indeed, the same could be said of prime matter, which is in potency to all forms. But matter, as we said, has no actuality or identity of its own at all. It simply is all things, though only in potency. By contrast, the point here is that we have a single form and act, the soul, which is quite distinct in its own nature from the forms of other things, and which in that sense is only itself and not all things, even in potency; but which is also in a way a form of all things, insofar as it has potency for the forms by which all things are actually cognized. It is the “place of forms.”184 Or better, as Aristotle says in the course of spelling out the thesis that the soul is in a way all things: just as the hand is the “tool (organ) of tools,” i.e., the tool in or by which all tools are used, so the soul is the “form of forms,” i.e., the form through which the forms of all cognizable things, as such, can be in act and render the things actually cognized.185

We should be struck, I think, by the extent to which Aristotle and Thomas regard being cognizable as a genuine feature of things, despite its being actualized only in a few special kinds of things (partially in the beasts, and fully in man). And we should be even more struck by the fact that this actualization is itself attributed to things, even though it does not inhere in them. It is their act of being cognized. To be sure, their own existence, and even their being as they are cognized to be, does not at all depend on this act. In that sense it is merely accidental to them. But it is still theirs. It is so as their effect; and, unlike other effects, it is an effect that in a way contains them. For in it, they manifest themselves or present themselves.

The Perfection of the Cognitive Soul: Cognition and Immateriality

But why are the cognitive likenesses themselves not in the things? If all things have forms, why is that not sufficient for their having at least some measure of cognition? Why is cognition actualized only in or through this special form, soul? Or rather—since plants have souls too—through certain special souls? Thomas’s article on God’s knowledge continues:

Now the contraction of a form comes from matter. Hence, as said above, forms, according as they are more immaterial, approach to a kind of infinity. So it is clear that a thing’s immateriality is the reason why it is cognitive; and the mode of cognition is according to the mode of immateriality. Thus it is said in De anima II [12, 424a32–b3] that plants do not cognize because of their materiality.186

Cognition and materiality are inversely proportional.187

Earlier we remarked that plant-soul enjoys a certain transcendence with respect to matter, insofar as it is not absolutely tied to the portion of matter that it actualizes now. But this is not the immateriality that Thomas is talking about. He is talking about being in some way or in some respect free of, or not conditioned by, any matter. I suspect that for most of us the initial reaction to this is simply to wonder what in the world matter has to do with it. If we recall the specifically Aristotelian doctrine of matter, however, we should be able to see the point.

In that doctrine, as we saw, matter’s primary role is that of a subject of change; and more precisely, a subject of the sort of change that is either itself a motion or at least (as in the case of substantial change) connected with motion. Such change involves a succession of mutually exclusive or contrary forms. In the matter, then, the forms are incompatible with each other. This point is not confined to prime matter and the substantial forms received therein; it applies to anything that functions properly as matter for any sort of forms. What is matter for heat and cold cannot have the forms of heat and cold together (in the same part), any more than a thing can be hot and cold together (in the same part). And if it is hot, the form of heat that it has is strictly its own form, not anything else’s, just as its being hot is not anything else’s being hot. But as we saw, what perceives or knows by a form of heat is not thereby hot; and the form that it has it not solely its own, but is also of what is perceived or known as hot through it. So the form of heat is in it, not according to the sort of potency that characterizes matter, but according to potency of a different sort. It is a potency that follows the cognizer’s specific nature as cognizer, and it is the result of the cognizer’s substantial form. The substantial form does of course inhere in some matter, but with respect to this potency, it is in some respect free of matter or not conditioned by it.

This thesis can be confirmed through other points of comparison and contrast between forms in matter and cognitive likenesses. For example, in acquiring the cognitive likeness of something, the cognizer passes from potency to act; but such passage does not strictly entail the loss of anything, even of another likeness. One can see red and green at the same time. Nor is the red seen with one part of the eye, and the green with another; the whole eye is seeing them both. As fashion designers know, one sees the combination. Again, taking on a cognitive likeness does not require a continuous passage from one’s original condition through an intermediate zone. One may pass at once from feeling something hot to feeling something cold without feeling anything lukewarm, or from seeing white to seeing black without seeing gray. This is to say that the cognitive power is equally, immediately ready for all the likenesses that it can take on; it is a kind of mean with respect to them.188 Matter is not equally ready for all the forms, accidental or substantial, that it might have. The form in it now makes it more ready for some than for others. Recall the example of wine and vinegar.

Moreover, the cognitive power’s capacity for various forms positively excludes their material presence in at least some part of the cognizer. For instance, a part of the eye must be colorless; the ear must be silent; the nasal passage, odorless; the tongue, tasteless. It is true that the organ of touch is not entirely without tangible properties. That is impossible. But the organ is in a mean or middling condition—neither very hot nor very cold, neither very hard nor very soft—so that it is at least free of the extremes and hence open to their cognitive likenesses.

There is also a significant difference between the activity to which matter is subject and cognitive activity. Not all cognitive activity is a change or a motion. The simplest sort is not. To be sure, the acquisition of the cognitive likeness of something is a change. But properly speaking, that change is not the very act of cognizing (perceiving or knowing) the thing. It is only that act’s origin. Seeing something is not a process of acquiring the visual likeness of it. Rather, one sees it in virtue of already having acquired that likeness. Of course, the thing seen may be changing, and one sees the change. But the seeing does not constitute another change.

Acts of this sort—seeing something, understanding something, and also appetitive acts such as desiring or wanting or being pleased at something—are what Aristotle calls perfect or complete activities. He is contrasting them with motions, which are imperfect activities.189 A motion is a process toward a form not yet had, an act of something in potency, as such. A perfect activity is simply the exercise of a form already had, remaining in that which has it. To be sure, even a motion proceeds from a form, in its agent. But the motion is not in the agent. It is in what is acted upon and moved. This is what is called transitive action, passing from the agent into what is acted upon and moved. And what is moved undergoes the motion just so long as it does not yet have the form that defines or specifies the motion. In some cases, of course, the agent and what is moved or acted upon are parts of one whole. The whole is then said to move itself. This sort of activity is what plants have. They develop themselves or transform themselves through the mutual interactions of their parts. But a perfect act remains in the very agent, and (in the case of a thing with parts) in the very part, from which the act proceeds.190 It does so even if the form that defines it is the form of something else. For (to repeat), in cognition, the form of the cognizer and the form of the object cognized are one and the same. It is the likeness of the object cognized, in the cognizer. Action remaining in the agent, as such, is called immanent action.

This notion of immanent action helps us see that the substantial form of the cognizer is a more perfect form—a more perfect principle of activity. Thomas writes,

In things that share in cognition, [substantial] form is found in a higher way than in those that lack cognition. For in things lacking cognition, there is found only a form determining each to one proper being (esse), which is the natural being of each . . . . But in things that have cognition, each is determined to its proper natural being, through its natural form, in such a way that it is nevertheless receptive of the cognitive likenesses (species) of other things . . . and thereby, those things that have knowledge approach in a way a resemblance of God, “in Whom all things pre-exist,” as Dionysius says.191

From here Thomas goes on to argue that what has cognition, having a more perfect substantial form than what does not, also has a more perfect mode of appetite. It has not only fixed physical tendencies but also the capacity to incline to things that it apprehends, insofar as these pertain to its own good.192 It is, in short, a more perfect nature.

The Qualified Immateriality of Sensation

Now, Thomas does regard sensation and intellect as two levels, quite distinct. In a passage quoted earlier, from the article on God’s knowledge, Thomas said, “the mode of cognition is according to the mode of immateriality.” Both cognition and immateriality, then, come in various modes. In fact, there are varying degrees of immateriality. The same passage goes on: “but sense is cognitive because it can receive cognitive likenesses without matter, and the intellect is still further cognitive, because it is more separated from matter and unmixed, as is said in De Anima III [4, 429a18, b5].” Intellect is “unmixed,” by which he means, not intrinsically conditioned by matter at all; we will consider this shortly. But sensation has only a qualified mode of immateriality. Against what he takes to be Plato’s view, Thomas insists that, for Aristotle and in truth, sensation is exercised by a bodily organ.

But let us go back to where Aristotle says that plants do not have sensation on account of their materiality. He also says there that all the senses receive forms without matter. Yet he illustrates this idea by comparing the senses with wax that receives the imprint of a signet-ring without the iron or the gold. And he goes on to say that what does the sensing is an extended thing, a body—a sense-organ.193 Is this even coherent? How can a body receive anything without matter? And is immateriality not all or none? How are there degrees of it?

Here again it is crucial not to forget that, in Aristotle’s lexicon, matter is a relative term. It does not refer only to prime matter. Wax contains prime matter. But his point here is that it is not, and does not contain, the matter of a signet-ring. A signet-ring must be made out of something hard, something that keeps its shape, such as iron or gold. The wax gets the ring’s shape without thereby becoming another ring. The nature or the essence of a signet-ring (in the sense in which an artificial thing has a nature or essence) includes not only the form but also a determinate type of matter, the type needed for being a signet-ring. It is just what we saw earlier: the cognitive likeness of a thing does not make the cognizer be a thing of the same sort.194 The eye receives the form of yellow, but without the type of matter that the form of yellow must inform in order to make something be yellow. And so the eye seeing yellow is not thereby yellow itself.

The wax has the form of the ring without being a ring. For that very reason, it can be a sign of the ring. If the form were impressed in another piece of iron or gold, that would not be a sign of the ring; it would be a counterfeit ring. Moreover, the ring has the power to signify the king’s authorization, but the ring by itself does not actualize this power. The power is actualized in the wax, because of its capacity to receive the ring’s form without its matter. Likewise, a sensible thing’s power to be sensed is actualized in the sense-organ, because of a similar capacity in it.

So understood, the “immaterial reception of form” is an utterly commonplace affair. It is how the images and the music are on your hard disk. Your hard disk neither looks like the images nor sounds like the music at all. It has the forms, or as we say, the information, of them, but not in the sort of matter in which these forms make images to see or sounds to hear.

Of course, the wax does not perceive the king’s authorization. Nor does the hard disk see the images. Why not? Because they do not have soul! This is not sudden mystification. It is just the general point that we are considering: the gradation of substantial forms. Some are more perfect than others, and this means, less conditioned by matter, in their own being and in their operations. The wax and the hard disk do not have substantial forms that are perfect enough to make any use of the forms-without-the-matter of rings or of images or of sounds. The wax and the hard disk can only function in the way the media of the senses do, transmitting such forms to what can use them to perform the vital activity of cognizing. What can use them in that way must be alive and have a form that is a soul, one even more perfect than a plant’s.

But how can Aristotle be so sure that the sense-powers are still forms inhering in bodily organs, and that the organs themselves are not just media by which the likenesses of things reach the powers? He is sure because he finds that the powers themselves show the traits of forms-in-matter: involvement in contrariety and process. A sense-power can be weakened, taking time to recover; and it can even be destroyed. What shows that it is really the power itself which is weakened or destroyed is that what weakens or destroys it is its very own activity, as initiated by its very own object.195 Seeing a bright light dazzles, so that for a while one cannot see dimmer things, and it may even blind; hearing a very loud sound deafens; etc. There is then, a material dimension that is essential to these powers. Their activities are not primarily bodily motions, but bodily motions are inseparably, essentially joined with them, as instrumental to them.

So the senses have a certain immateriality, but it is qualified. Thomas also finds diverse grades of immateriality among the various senses. Touch is the most material; even though it gets the form of the tangible body without the matter, as when your cold hand feels the water’s warmth, this is accompanied by the material reception: your hand does gradually get warmer. Touch is also the most limited as to the distance of its possible objects from it. At the other extreme is sight, whose activity involves a minimum of material change and which extends very far indeed. Then there are the so-called interior senses, such as memory, which other animals also have; these serve to combine, preserve, and evaluate the data of the external senses. They do not even need the object’s material presence outside the soul. They extend to past and future (perhaps merely potential future, never actualized). But they too, Thomas holds, are in an organ. Today, I assume, he would say it is the brain.

The Total (Intrinsic) Immateriality of Intellect

Only intellectual activity, then, is “separate and unmixed,” not seated in a bodily organ at all. A sign of this is that strong objects do not affect it in the way strong objects of a sense affect the sense.196 There is no such thing as something’s being so intelligible as to render its knower dull-witted or stupid. Grasping highly intelligible things does not make grasping lesser ones harder, but if anything, easier.

Thomas’s fundamental proof of the total immateriality of intellect, however, invokes once again the notion of a power’s amplitude and extension. By intellect, he says, we can know the natures of all bodies.197 But if it had any bodily nature of its own, or an organ with such a nature, that would obstruct the knowledge of others, just as the pupil’s having some color would obstruct the vision of other colors. He is saying that, in matter, the forms of bodily things are opposed or contrary to one another. But none of them is opposed to intellect. Nor, as they are in intellect, are they opposed to each other. Grasping one is perfectly compatible with grasping others. Intellect’s proper seat, then, is not a body.

A further argument rests on the way in which intellect knows the natures of things.198 It knows them “absolutely.” This does not mean that it knows them perfectly or exhaustively, but that it knows them in a pure way, unconditioned by factors extraneous to them. For instance, it knows stone absolutely, just as stone. It grasps the nature of stone just in itself, according to its own formula or ratio—the nature common to all stones, anywhere, anytime. It is not grasping only this stone here and now, in the way the eye is seeing only this patch of blue. But this means that intellect itself must be an “absolute form,” not inhering in matter. Otherwise its cognitive likenesses of the natures of things would be under the conditions of its own matter, and it would grasp the natures in a correspondingly conditioned and individual way.

Intellect, then, enjoys a kind of infinity. It embraces all natures, without limit, and it bears on each in the unlimited, universal extension of the nature’s own absolute formula. Earlier in the article on God’s knowledge, Thomas had in fact said that “the contraction of a form comes from matter. Hence, as we said above, forms, according as they are more immaterial, approach more to a kind of infinity.” The reference is to STh, I, q. 7, a. 1, which is on God’s essential infinity. There Thomas presents God’s infinity as that of a form not contracted by matter. His argument turns on the thesis that “form, considered in itself, is common to many, but by being received in matter, it becomes determinately the form of this thing.”

It may sound as though he is speaking only of forms that are abstract and universal—i.e., commonly predicable of many things—and that are individuated by being applied to matter. That is indeed an example of what he is talking about, but it can hardly be the only one. I say this because his aim here is to show that God is infinite, and he certainly does not think that God is a universal. But besides universality or common predicability, there are also other ways of being common to many; and some of these ways can belong to individual forms.199 A form can be one, or in one thing, without being “determinately of” that thing, i.e., of it and of nothing else. Thus, a cognitive likeness is an individual form in the cognizer, but it is an act of both cognizer and cognized. And a cognitive power is an individual form in the cognizer, but it is a potential of the things that are its objects, a potential for their being cognized. This is exactly how the intellect is in a way “all things.” In the case of God, Thomas will say that His intellect, which is identical with Him, is itself the act of all the intelligibles, the act of the whole of universal being.200 This is because, as he says in STh, I, q. 7, a. 1, God is an act of being, esse, that is not received in any subject, and because esse is what is “most formal of all.” And so, as Thomas concludes in our article on God’s knowledge, existing at the summit of immateriality, God is at the summit of cognition.

These assertions about God are highly metaphysical and involve notions that we will try to clarify in the next two chapters. But for the moment what I wish to stress is that Thomas is saying that an individual intellect is a form not received in matter, and that this is why it is common to many, “in a way all things.” Your intellect is so. It is so despite its being in you and your being corporeal and material. This is what the Averroists found unintelligible: that a form which does not and cannot inhere in matter should belong to a material being.

Thomas knows that his position is delicate. But he thinks he can avoid sheer incoherence, again by distinguishing between this power of the soul, intellect, and the essence of the soul itself as a substantial form. The intellect is not a substantial form; it is an accident, a quality. But the substantial entity that it properly inheres in is not a body. It is the soul itself. The soul, in its turn, does inhere in matter, thereby constituting a human being. In fact the whole soul inheres in matter. There cannot be part of it in matter and part outside. It is simple, all or none. It does not even have distinct substantial parts. If it did, it would need another soul to hold them together. Nevertheless, its intellect is not in matter, in the sense that it is not at all intrinsically conditioned by matter. This cannot be imagined! But we can at least see that it is not a merely ad hoc solution. The intellectual soul stands at the peak of a whole hierarchy of forms, each higher one being less conditioned by matter. The senses have a qualified immateriality. Plant-souls are not tied to this matter. Every substantial form overcomes the divisibility of matter and makes a body an unqualified unity, a substance in act.

The immateriality of intellect is crucial in Thomas’s understanding of the being of the human soul and its destiny after a person’s death. This too is a metaphysical topic that we will look at later. There we will see how Thomas ties the human soul’s possession of intellect to an especially high grade of perfection as a substantial form.

That you have your own intellect and are exercising your own understanding is also crucial, on Thomas’s view, for ethics. Otherwise you would not be making any free choices. Freedom of choice is rooted in the enormous amplitude and extension of the properly intellectual appetite, the will. This is the most perfect of appetites, inclining toward the good in an absolute way, as good, in all its multiform universality.201

The Intellect of an Animal

But we must not lose sight of the fact that what is doing the understanding (and willing) is, for Thomas, in the genus of animals. It is—you are—a natural, physical being. This has serious consequences for the intellect itself. Even if it is not intrinsically conditioned by matter, matter does condition it in an extrinsic way, and the conditioning is quite pervasive, because it regards the intellect’s very object. Intellectual activity is not performed by a bodily organ, but ours is inseparable from the activity of a bodily organ. This is because it has to have an object. There is no such thing as understanding without understanding something. But our intellect finds its object in something presented by the senses; in particular, in what he calls a phantasma, an image, produced by the interior senses. This is why, if the brain is injured, understanding may be hampered or suspended. It is not that intellect itself is damaged, as by an object that is too strong. It is that its contact with its object is rendered faulty.

Notice that even if the external senses are operating, without a phantasma the intellect cannot work. Thomas often speaks of the intellect “abstracting” its object, which is a nature taken absolutely and universally, from the phantasmata. This might sound as though it is a question of stripping away a thing’s particular sensible features and pulling out the nature underlying them—almost as though those features conceal the nature. In that case, it would be hard to see how a phantasma is of much help. But instead of stripping away or pulling out, a better metaphor would be compressing and unifying. (To be sure, in the process something does get squeezed out; but it is only matter.) We are talking about the nature of a bodily thing, and about a grasp of that nature that has its origin in the nature itself, in its self-presentation. This is through the body’s sensible features, of course. But a mere photograph will not do. What is needed is more like a video-clip, or several of them, capable of running at extremely high speed. A bodily nature is strictly a nature, a principle of motion and rest. It shows itself through the motion and rest that it is principle of, and we grasp it by discerning the unity in that motion and rest. Even the nature of a stone presents itself piecemeal. In order to grasp it, we need to put the features and parts and episodes together, in such a way that the unifying logos or ratio or proportioning that runs through them stands out. This work of synthesis, this “spiritualizing” of a bodily nature, is prepared by the interior senses. But it is brought to completion by the intellect itself, and it is only the intellect that directly grasps that logos. The unity of a subject of change, substantial unity—which is seen above all in identity through change202—is a strictly intelligible object.

Thomas is not saying that we can only think about sensible things. We are now thinking about intellect and soul, which are not sensible. But the natures of sensible things, he says, are the first and most fully proportionate or adequate objects of our intellect.203 Thinking about anything else requires some sort of connection or comparison with such natures. For instance, we can think about God only because we have phantasmata of His effects—and only to the extent that He can be thought of in terms of those effects.204

As Thomas sees it, our intellect’s dependence on the senses explains many features of its activity; in particular, the fact that it does not grasp everything all at once. As befits the power of a natural being—a growing being—it proceeds towards its due perfection or maturity gradually.205 It starts with a general and confused knowledge of things and works toward more proper, distinct knowledge of them.206 Thomas even likens it to prime matter, since it is by nature merely in potency to intelligible forms, as prime matter to natural forms.207 Its discursiveness even serves to sum up the difference between it and the other intellects, divine and angelic. It, and it alone, is the reasoning intellect.208

To say rational, then, is already, implicitly, to say animal. According to Aristotle, this is one of the features of a good definition: the ultimate differentia implies all the others. In that way it captures the whole form, and everything entailed by the form, of what is being defined.209 Rationality is a mode of intellect—of the quality of being, in a way, all things—and hence it implies a dimension of pure immateriality. But it is the mode that is intrinsically connected to the life of the senses, and therefore to the sense-organs; and to the vegetative functions and the physical ingredients that constitute the organs; and to matter itself. That there is such a differentia is itself proof that what is defined—in this case, man—is indeed of one nature, not a mere combination. Thomas calls this a “wonderful connection of things.”210

At the same time, he also thinks that we should not be too surprised to find that what is highest in the corporeal order, namely the so finely tuned human body, should be joined to what is lowest in the spiritual order, namely that intellectual substance which is the human soul.211 Of course, as we have seen, the body exists thanks to the soul itself, which is its formal principle. That is why the nature is one: it has one form. And thus,

the intellectual soul is said to be a sort of horizon and border of corporeal and incorporeal things, inasmuch as it is an incorporeal substance and yet the form of a body. For something made out of intellectual substance and bodily matter is not less one than is something made of the form of fire and its matter, but, if anything, more so; because the more a form dominates matter, the more what is made from it and matter is one.212

In the ensuing lines, Thomas takes the reader by the hand through the various grades of form that we have already surveyed.

In calling the human soul a substance, Thomas does not just mean that it is a substantial form. He really means a substance, in the sense given earlier: a subject of being, at least a partial one.213 This is a very metaphysical point, and I shall put off discussing it until chapter 5. But before closing this one, let me briefly address a strictly physical concern.

The concern, in a word, is neuroscience. Thomas knew that the human body was finely tuned, but really he had no idea how fine the tuning is. For that matter, he had no idea how finely tuned, or at least how complex, a mineral body is. Can his account of human cognition, and with it, of human nature, or really of any physical nature, still be taken seriously? Would even he think it could? After all, as we saw, he holds that the complete definition of a natural thing’s kind expresses not only its form but also its specific matter or material dispositions. If, as it seems, he is wrong about the matter of things, can he have gotten their forms right?

I can only venture a guess at what his own answer would be. I think he would say that it depends. In some cases, indeed, the sheer possibilities of observation that he had available were so limited that he got both the matter and the form wrong. I am thinking of his account of the heavenly bodies. But there the main problem was the inability (now overcome only in part) to observe the bodies themselves, as the whole beings and subjects of activity that they are. He was wrong about what they were actually doing. The situation is different with the things that he had under his nose (and behind it). No amount of experimenting, for instance, will overturn the thesis that we can think about things in a universal way.

People sometimes say that neuroscience has rendered the idea of the mind’s immateriality obsolete. But surely, if Thomas’s argument for that is invalid now, then it was invalid in the thirteenth century too; and if it was valid then, it still is. For his argument is to the effect that no matter what the brain (or any other body) is doing, it cannot be understanding. More mere evidence about what it is doing is therefore simply irrelevant. But in fact, when people say that, they hardly ever have in mind Thomas’s argument for the immateriality of intellect. They almost always take the issue to be the status of consciousness. But for Thomas, some consciousness, the sensitive sort, is indeed in an organ. Ever since Descartes, the deep distinction between intellect and sense that Aristotle urged against his predecessors has been obliterated. And even regarding the qualified immateriality of the senses: more evidence about (say) the eyes is irrelevant to Thomas’s main thesis, which regards the amplitude and extension of sensation, and which pretty much boils down to the claim that your eyes (or whatever you see with) are in your head, while that which you are directly seeing is not in your head but on the page in front of you.214

If we have a clear grasp of what something as a whole is doing, then we can have a valid conception of its form, even if we are in a good deal of ignorance or even error about its parts and matter. And the conception of the form should precede and guide the inquiry into the matter. If we lose sight of the whole, we cannot grasp how the parts function as parts, as we cannot grasp the potency apart from the act. Wholes and forms are naturally prior in intelligibility. According to Thomas, this is how Aristotle proceeded with organisms.215 Among Aristotle’s biological works, Thomas says, the one that comes first (doctrinally, not chronologically) is the De anima. It treats the soul—the form—in a certain abstraction from the body and the matter. The subsequent works involve “concretion” or application to the body, first in general ways—for instance in the treatise on the senses, which are common to all animals—and then with respect to each particular kind of animal or plant. Thus, being prior, the abstract treatment can be valid even if there are problems in the subsequent “concretion.” The form allows for a certain amount of free play in the matter. How could it be otherwise, if the thing is mobile?

This could explain why, while many of Aristotle’s biological works are ignored today, the De anima is still taken very seriously. It can be, if hylomorphism in general is valid. And experimental science can hardly be what decides that.216

Thomas also remarks that there is no such “concrete” treatment of the intellect, because it has no organ. Its greatest “concretion” is in the soul itself (which is not a body, but is still of a body), while the most abstract treatment would regard the separate, totally immaterial substances. They are the ones that are by nature absolutely first in intelligibility. Their consideration, however, pertains not to natural science, but to metaphysics.

135. https://www.oxforddictionaries.com/definition/english/soul.

136. STh, I, q. 75, a. 1.

137. STh, I, q. 2, a. 3.

138. On the question and argument of STh, I, q. 75, a. 2, see below, 111–13.

139. See above, 12.

140. See above, 28.

141. STh, I, q. 90, a. 4, ad 2. See my “The Physical Status of the Spiritual Soul in Thomas Aquinas.”

142. Robert Sokolowski, in “Soul and the Transcendence of the Human Person,” suggests using the word animation instead of soul. It is a very helpful essay, both on the notion of soul and on that of spirit.

143. On the meaning of life, see STh, I, q. 18, aa. 1 & 2.

144. De anima, II.1, 412a13–21. Here the word that act translates is entelecheia, meaning a perfection or a completion. Aristotle connects entelecheia and energeia in Metaph., IX.3, 1047a30–b2; IX.8, 1050a23; cf. Physics, III.1, 201a3–202b29 and Metaph., XI.9, 1065b5–1066a34.

145. De anima, II.4, 415a23–25.

146. De anima, II.4, 415b11–14. See In De an., II, lect. 7, §319.

147. De anima, II.1, 412a22–28 & 412b25–26. See STh, I, q. 77, a. 1. Thomas calls activity “second act.”

148. See In De an., II, lect. 1, §225.

149. See STh, I, q. 76, a. 3, ad 4; a. 6, ad 1 & ad 2; below, 100–101.

150. De anima, II.4, 415b28–416a18. The doctrine of the elements in this discussion is, of course, obsolete. But that need not affect the essential points much, at least not if hylomorphism in general is valid. See below, 81–82.

151. Interpreters of Aristotle have offered different accounts of how the elements remain present in what he calls “mixed” bodies and in organisms. For Thomas’s view, see STh, I, q. 76, a. 4, ad 4; q. D. De anima, a. 9, ad 10.

152. See STh, I, q. 76, aa. 3 & 4.

153. De anima, II.1, 412b6–9.

154. See Metaph., VIII.6, 1045a7–b23.

155. See Metaph., V.6, 1016b1–11.

156. See Sokolowski, “Soul and the Transcendence of the Human Person,” 155–57. The soul belongs primarily to the whole organism and secondarily to the parts, by reason of their order to the whole: STh, I, q. 76, a. 8. In general, parts are more on the side of matter, and whole is more on the side of form: STh, I, q. 7, a. 3, ad 3.

157. See Physics, II.1, 193b8–18; II.8, 199a23–32.

158. See STh, I, q. 5, a. 4.

159. The theme of grades of life in Thomas extends beyond the idea of soul (which applies only to organisms) and reaches all the way to God; see John Boyle’s elegant and rich essay, Master Thomas Aquinas and the Fullness of Life.

160. De anima, II.3, 414b19–415a13; STh, I, q. 76, a. 3 (toward the end of the corpus).

161. See STh, I, q. 77, a. 8. On the unnatural condition of the separate soul, see below, 116.

162. See Eberl, Thomistic Principles and Bioethics, 43–61 (though I demur on whether whole-brain death entails the loss of integrative functions). Notice too that what Thomas himself posits, both in the process of generation and in the phases following death, is a series of incomplete, unstable forms (In De generatione et corruptione, I, lect. 8, §60[3]). So if the integrative vegetative functions are stable and going on indefinitely, then on his view, the body cannot have lost its human soul; it is not only still alive but also still a person. (Regarding generation, however, I am not suggesting that today Thomas would hold to the idea of a succession of forms. I do not think he would. See Eberl, 23–42.)

163. Thomas often uses the Scholastic term for this, quiddity, which literally just means whatness. The words quiddity, nature, and essence all refer to the same reality, but they have different connotations. Quiddity indicates its answering the question, “what is it?” Essence expresses its functioning as that in and through which the thing has being. Nature points to its role as principle of activity. See the beginning of chapter 1 of De ente.

164. See STh, I, q. 78, a. 1.

165. There are appetitive powers that bear on things apprehended by the senses, which are capacities for feelings or emotions, such as hunger or sexual desire or fear; and there is one that bears on things apprehended by intellect, namely the will: STh, I, q. 80, a. 2.

166. See above, 39.

167. For “rises above” (supergreditur), see STh, I, q. 78, a. 1. For “exceeds” (superexcedit, excedit), see Scg, II, cap. 68, §1454–59; STh, I, q. 76, a. 1, and q. 78, a. 1.

168. STh, I, q. 76, a. 7, ad 3. The notion of act as standing out from potency reflects Aristotle’s language in his account of energeia in Metaph. IX.6. He speaks of a statue or a half-line being potentially in a block of wood or in a whole line because they can be “pulled out” (aphairethein, 1048a33); and he says the infinite can exist potentially but not actually because it cannot exist “separately” (chōriston, 1048b15; chōrizesthai, 1048b17).

169. Thomas insists on this point: STh, I, q. 119, a. 1.

170. See In De gen., I, lect. 17, §118.

171. On reproduction as essentially communication of form, it being incidental whether any matter passes from generator to offspring, see STh, I, q. 119, a. 2. How living things are properly classified, and the ontological status of their species, are matters of much dispute now, and applying Thomas’s thought to the issues would be very complex. But all do agree, I take it, that living things tend to generate things quite similar to themselves.

172. STh, I. q, 78, a. 2.

173. On the perfection of form as a sort of quantity, see STh, I, q. 42, a. 1, ad 1 (discussed below, 134–35).

174. STh, I, q. 14, a. 1.

175. STh, I, q. 4, a. 3.

176. De anima, I.2, 404b8–18, 405b12–23; I.5, 409b23–410b10.

177. See STh, I, q. 85, a. 2. As he points out there, if the likeness itself were what is cognized, then all appearances would be true. There could be no disagreement or dialogue. We would never be talking about the same things.

178. Sensitive consciousness is one of the functions of the so-called “common sense”: See STh, I, q. 78, a. 4, ad 2. On why the cognition of the cognitive act is secondary, see my “Intentional Being, Natural Being, and the First-Person Perspective,” 113. This is not to say that self-knowledge is of little significance in Thomas’s thought; quite the contrary. See the excellent study by T. Cory, Aquinas on Human Self-Knowledge.

179. Physics, III.3, 202a13–b22.

180. See In De an., III, lect. 2, §592–93.

181. Cf. De anima, II.5, 417a19–21.

182. De anima, III.7, 431a1–2. See In De an., II, lect. 12, §377.

183. See In De an., III, lect. 13, §788.

184. De anima, III.4, 429a27–28.

185. De anima, III.8, 432a1–3.

186. STh, I, q. 14, a. 1.

187. STh, I, q. 84, a. 2.

188. De anima, II.11, 424a2–10; II.12, 424b1–3; III.13, 435a21–22.

189. De anima, III.7, 431a3–8; Metaph., IX.6, 1048b18–36; cf. EN, X.3, 1174a13–b14. See STh, I, q. 18, a. 1 and a. 3, ad 1. Of course, there can be a progressive series of such acts, which resembles a motion; e.g., learning or reasoning.

190. Metaph., IX.8, 1050a23–b6. Cf. STh, I, q. 18, a. 3, ad 1; q. 54, a. 1, ad 3, & a. 2; q. 56, a. 1; I–II, q. 74, a. 1.

191. STh, I, q. 80, a. 1. The cognitive likenesses that the senses and human intellect get from bodily things do not give natural being; nor do they give natural operation. “The heat in the fire, not in the soul, heats” (De ver., q. 22, a. 12). The greater extension of these cognitive likenesses, as opposed to that of the soul itself, is bought at the cost of a certain weakening or denaturing. Thomas calls this weak mode of forms “intentional being” (esse intentionale). This mode, however, is not essential for all cognition; some natural forms, such as the angels’ and God’s, are naturally immaterial, and so they are per se principles of actual knowledge. Thomas’s esse intentionale is thus related to, but not the same as, the modern notion of intentionality; I discuss this at length in “Intentional Being, Natural Being, and the First-Person Perspective.”

192. That is why the likenesses of other things exist in it without the inclinations or active tendencies that are proper to them in the things themselves. In that case it would tend toward their good, not its own.

193. De anima, II.12, 424a17–28.

194. It does not give the cognizer “natural being”: see above, 71–72.

195. De anima, II.12, 424a28–32; III.4, 429a29–b5.

196. De anima, III.4, 429a29–b5. See STh, I, q. 75, a. 3, ad 2.

197. Here I follow the argument as given in STh, I, q. 75, a. 2. Nowhere, as far as I know, does Thomas argue for the thesis that we can know all bodily natures. How can he be sure of this? I do not think he assumes that we have actually known them all. He is only saying that our minds are open to them all. Perhaps the point is simply that we already do grasp the general nature of body. That casts a net over the whole field. All specific bodily natures must fall under it. Notice that the senses cannot do anything like this; one cannot see color in general.

198. STh, I, q. 75, a. 5.

199. Very explicit on this point, and very much in line with STh, I, q. 7, a. 1, is In De an., II, lect. 5, §282–83.

200. STh, I, q. 79, a. 2; I–II, q. 51, a. 1, ad 2. Elsewhere he says that God is “act and likeness of all things” (De ver., q. 20, a. 2). And he says that, whereas our intellect is in potency to the forms of all things, God’s form naturally contains them all in act, as the perfect contains the imperfect: STh, I, q. 4, a. 2, and I, q. 14, a. 6.

201. See, inter alia, STh, I, q. 59, a. 3; q. 82, a. 2, ad 1; q. 83, a. 1; I–II, q. 9, a. 6, ad 3; q. 10, a. 1, ad 3; q. 13, a. 6. Generally on Thomas’s conception of the will, see the excellent study by David M. Gallagher, “Thomas Aquinas on Will as Rational Appetite.”

202. See above, 40.

203. STh, I, q. 87, aa. 4 & 7.

204. STh, I, q. 12, a. 12, ad 2. This is true even of the knowledge of God that comes through grace: STh, q. 12, a. 13.

205. See STh, I, q. 79, aa. 4 & 8; cf. I, q. 14, a. 7, and I, q. 58, aa. 1, 3, & 4.

206. See STh, I, q. 85, aa. 3, 5.

207. STh, I, q. 87, a. 1; see STh, I, q. 56, a. 1. And thus Thomas can explain spiritual changes without having to posit spiritual matter to make them possible. See above, 13.

208. STh, I, q. 79, a. 8.

209. Metaph. VII.12, 1037b8–1038a35; cf. In Meta., VII, lect. 12, esp. §1555–65.

210. Scg, II, cap. 68, §1453.

211. Scg, II, cap. 68, §1453. On the suitability and dignity of the human body, see STh, I, q. 76, a. 5; q. 91, passim.

212. Scg, II, cap. 68, §1453.

213. See above, 39–40.

214. A similar point also holds regarding Aristotle’s response to Empedocles’s account of plants (see above, 56–57). The doctrine of the four bodily elements is obsolete, but it is also beside the point as regards the question whether a plant functions as a single nature or a mere combination.

215. Sentencia Libri De sensu et sensato, Proem.

216. On Thomas’s hylomorphism in relation to contemporary philosophy of mind, see Madden, Mind, Matter, and Nature.

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