7. § 7. Principles in Science.
§ 7. Principles in Science.
A. Rationalism.
. Science always consists in a logical relation between subject and object. The relation in which we place these two to one another determines our conception of science. At all times there have been two directions which in this respect stand diametrically opposed to one another,
Rationalism and Empiricism. They already arose in Greek philosophy.
Already there the antithesis was made of αἰσθησις and λογος, of sensible perception and thinking, and thus also of δοξα and ἐπιστημη. The school of Elea, Plato, the Neoplatonists stood on the side of rationalism; sensible perception gives no knowledge, it has as object changing phenomena, and teaches us only [146] to know that something is and is thus, but not why it is thus; moreover it deceives us many a time and furnishes us with false representations, e.g. the crooked stick in the water, the rising sun etc., which
only by thinking can be purified of their untruth. Therefore thinking stands far above sensible perception. This alone yields us ἐπιστημη; science does not come from without, it is a product of the human spirit. In more recent philosophy this rationalistic direction has arisen again with Cartesius, who, casting everything away, finally found his firm point of departure in thinking and from that concluded to being, cogito ergo sum. Therewith the necessity of thought, the logical connection, the mathematical order of ground and consequence became in Spinoza the standard of truth. The sensible world is at most occasion but not source of our knowledge, the human spirit can bring forth all knowledge out of itself, with its own means, thinking. Nos idées, même celles des choses sensibles, viennent de notre propre fond, Leibniz, Nouveaux essais sur l'entendement humain I ch. 1.
Kant has now indeed tempered this rationalism in so far as he derived not the matter but only the forms of perception from the human spirit
(transcendental, critical idealism). But Fichte rightly saw that such a distinction was impossible, and therefore declared that all elements of our knowledge, even up to perception itself, were a priori and were posited by the I (absolute idealism). Now this rationalism with these philosophers was still always limited to the domain of the faculty of knowledge, and thus was only meant in erkenntniss-theoretischen sense. But this subjective rationalism was by Fichte, Schelling and Hegel extended to an objective rationalism; not only knowledge, but also being, not only the representations but also the things themselves have arisen only out of thinking, thinking and being are one (metaphysical idealism). There is progress in this history of rationalism; thinking, not sensible perception, gives truth; it brings with it in itself the principia, the semina of all knowledge; it creates the form of our world of thought (Kant), and also its
matter and content (Fichte), indeed it creates and constructs the whole world, not only of thinking, but also of being. [147]
2. In whatever different forms this rationalism has also appeared, it nevertheless has always had one fundamental thought, viz. that the origin of knowledge is to be sought in the subject. It is good to understand that one arrived at this thought. For, apart from the unreliability of sensible perception, there is between the representations in us and the things outside us such an essential difference, that the former are not to be explained from the latter. Matter cannot act upon the spirit; spiritual phenomena, such as the representations are, are to be explained only from the spirit; like can only be known by like. From that it follows, that the existence and cooperation of matter and spirit, of things outside us and representations in us, either can only still be maintained by hypotheses such as occasionalism
(Geulinx), the harmonia praestabilita (Leibniz), the beholding of the ideas in God (Malebranche) etc., or that simply the duality of matter and spirit must be denied, and that thing and representation, being and thinking, are regarded as essentially one. For, thus says idealism, if thing and representation are two, then we must despair of the knowledge of the thing; we can, after all, never test our representation of the thing against the thing itself; we can never get out of ourselves, out of our world of representations; nous ne pouvous nous mettre à la fenêtre, pour nous voir passer dans la rue (Scherer). We always remain within the circle of our representations and never come into contact with the thing itself, but always again with our representation of the thing; only the conscious exists for us; I can think only the thought, not the thing, think; what is not my thought is for me unthinkable, unknowable, does not exist for me. And this idealism has then been further strengthened by what the physiology of the senses
now teaches. Already Democritus made a distinction between such properties as weight, density, hardness, which are objective and lie in the things themselves, and others, such as warmth, cold, taste, color, which are present only subjectively in our sensations, Zeller, Philos. der Gr. I4 783.
This distinction of objective and subjective, quantitative and qualitative properties was taken over by Cartesius, Hobbes, Locke, who first called them primary and secondary properties, An essay concerning human understanding, II ch. 8 § 19 etc., and then in this century especially worked out by Helmholtz in his Handbuch der physiol. Optik, [148] Leipzig 186566 and Lehre von den Tonempfindungen, Braunschw. 1862, 4e Aufl. 1877, cf. also Lange, Gesch. des Mater. 4e Aufl. 1882 S. 712 f. Pierson, Gids Juni
1871. According to this so-called semi-idealism there are outside us in the world only mechanical movements of the atoms, matter is without qualities.
Our senses receive only impressions through the movement and undulation of the atoms; those impressions are qualitatively alike; but in our brains we bring forth from those uniform movements the infinite diversity of the world of perception. Light, sound, color, taste, warmth, cold, all qualitative properties, which we suppose to perceive in the things, do not exist outside but arise and exist only in the human spirit. One and the same movement of matter, touching our sense of touch, makes the impression of warmth; and falling into the eye, it provides us the sensation of light. The world in its substance is not, but yet in its form is a product of man. Thus idealism has gained more and more ground in philosophy and has even received strong support from natural science.
3. Yet there are very serious objections against idealism. In the first place it is in conflict with all experience. We are by nature all realists, and the idealists themselves are so too in practice. In fact idealism is a matter, an
opinion of the school, which is in direct conflict with life and experience. It does not explain how and why every human being of himself and involuntarily comes to ascribe objectivity and independent reality to the perceived phenomena, and not merely to conceive them as inner states of consciousness, while we nevertheless clearly distinguish between internal states and external things, between what is in and outside us, between dream (hallucination) and reality. To this is added that the human being is never and in no single domain autonomous, but everywhere and always dependent on the nature around him. By his body he is bound to the earth.
Shelter, food, clothing he receives from it; it would be strange if intellectually it were otherwise with him. Just as we indeed prepare food and clothing with our hand, but nevertheless derive the material for it from the nature outside us, so too we receive with the intellect the material from outside. The intellect is also here [149] instrument, not source. Idealism identifies the organ with the source of knowledge, makes, as it were, the eye into the source of the light, derives thought from thinking. That, however, cannot be, because a thing and its representation, being and thinking, esse and percipi are two and cannot be identified. They are, after all, both toto genere different. A thing does not rise up in us like a dream, and also does not follow logically from preceding representations, but often comes suddenly from outside to me and breaks off the series of my representations, it is independent of me, and has an existence outside me; it has properties that cannot be ascribed to the representation of it. The thing that one calls a stove is, e.g., warm, but the representation that of that thing is in my consciousness has such a property not. If nevertheless thing and representation are identified with each other, idealism must lead to absolute illusionism; not only the world outside me becomes semblance, but I myself
also am nothing but a representation, a phenomenon for myself. Everything becomes a dream, there is no reality but also no truth any more. Idealism may now exercise no influence on the action and conduct of its adherents,
Land, Inleiding tot de wijsbegeerte, 's Grav. 1889 bl. 92 v. Fr. Paulsen, Einleitung in die Philosophie, Berlin 1892, S. 363, because life is many times better and stronger than the doctrine, yet it is not to be seen how, e.g., religion and morality are still theoretically to be justified, if both are no real relations to beings existing outside me but only to representations in me.
The dualism of thinking and being, from which idealism in Plato, Cartesius, Kant proceeds, then also always again turns into the identity of both in Spinoza, Fichte, Schelling and Hegel; subjective rationalism leads to absolute and objective rationalism. But abstract, contentless thinking, the most universal principle of substance, the absolute, the being, the thinking, from which idealistic philosophy then takes its point of departure, is not capable of producing rich full being. From that barren abstractum the living world, from that lifeless one the multiplicity of phenomena is not to be explained. The rock on which all pantheism is wrecked is multiplicity; no transition is to be found from the abstract to the concrete, from the general
[150] to the particular. Schelling therefore also openly expressed it, dass es schwer sei an die Wirklichkeit heran zu kommen, bij Liberatore, Die
Erkenntnisstheorie des h. Thomas v. Aquin, deutsch von Eugen Franz, Mainz 1861 S. VII. Finally, a distinction such as that of Kant between the form, which we ourselves bring along in perception, and the matter, which comes to us from outside, or such as that of semi-idealism between objective, primary and subjective, secondary phenomena is therefore untenable, because a boundary between both is not to be indicated. The matter of a representation belongs, as Fichte therefore also expressed, just
as much to the representation as its form. And the primary quantitative properties, yes also the bodies themselves, are just as much perceived phenomena as the qualitative properties of tone and color etc. There exists no reason to accept the testimony of one sense, touch, and to reject that of the other four, and thus to make an exception only for the properties of extension, hardness etc. There is no objection to ascribe to the forms of perception, time and space, and to the categories of thinking also objective reality in the things themselves. And the physiology of the senses does not prevent us from seeing precisely in the different quantitative relations and movements the objective ground of the qualitative phenomena, F. Pillon,
L'évolution historique de l'idéalisme, de Démocrite à Locke, in L'année philosophique, sous la direction de F. Pillon 3e année, Paris, Alcan, 1893, p.
77-212. Georges Lyon, L'idéalisme en Angleterre au 18e siècle, Paris, Alcan, 1888. Dr. Glossner, Der moderne Idealismus, Münster 1880. Ernst
Laas, Idealismus und Positivismus, 3 Theile Berlin 1879 f. E. von Hartmann, Kritische Grundlegung des transcendentalen Realismus, Berlin
1885. Id. Das Grundproblem der Erkenntniss-theorie, Leipzig, Bd. I Abth. 2 van de Ausgewählte Werke, S.
Id.
Neukantianismus, Schopenhaueranismus und Hegelianismus, Berlin 1877. Stöckl, Lehrbuch der Philos. 6e Aufl. I 363 f. E. L. Fischer, die Grundfragen der Erkentnisstheorie 1887 S. 49 f. Id. Theorie der Gesichtswahrnemung, Mainz,
Kirchheim 1891. Al Schmid, Erkenntnisslehre 2 Bde. Freiburg 1890 II 134141. L. Strümpell, Die Einleitung in die Philosophie, Leipzig, 1886, S. 165 f. Paulsen, Einleitung in die Philos. Berlin 1892 S. 354 f. C. A. [151] Thilo,
Die Wissenschaftlichkeit der modernen specul. Theol. 1851 S. 1-48. Flügel, Die specul. Theol. der Gegenwart 1888. J. T. Beck, Vorlesungen über Chr.
Glaubenslehre, I 1887, S. 44 f. F. J. Stahl, Philos. des Rechts, 5e Aufl. 1878
I 90 f. Nathusius, Das Wesen der Wissenschaft, Leipzig 1885, S. 265 f.
Gretillat, Exposé de théol. systém. 1885 I p. 63 s. Pierson, Contemplation, authority and experience, 1855, cap. 1 § 1. Opzoomer, Science and Philosophy, 1857, hoofdst. 1. Land, Inleiding tot de wijsbeg. 1889, bl. 82 v.
Bilderdijk, Treatises, concerning the doctrine of the soul, morals, and law, 1821 bl. 121 v: on causality, bl. 141 v. of the human understanding, etc.
B. Empiricism.
4. Diametrically opposed to Rationalism stands Empiricism, which already among the Greeks had its forerunners in the Atomists, then in the Middle
Ages appeared as Nominalism, subsequently as a philosophical direction in modern times made its entrance with Fr. Bacon, and, over Locke, Hume and the French Encyclopaedists, in this century has issued in the Positivism of A. Comte, the experiential philosophy of Stuart Mill, the Agnosticism of H.
Spencer and the Materialism of Büchner, Czolbe, Moleschott etc.
Empiricism too appears in different forms and systems, but nevertheless always has this principle as its point of departure, that only senseperception is the source of our knowledge. While rationalism lets the objective world be directed wholly or in part according to the human mind, empiricism subjects consciousness wholly and entirely to the world outside us. In the striving after knowledge, man brings with him nothing except only the capacity of perceiving; from that all intellectual activity takes its beginning and origin. There are therefore no innate concepts; all preconceived opinions the scientific investigator must set aside. From the temple of truth, which he wishes to build up in his consciousness, he must
remove all idola; no anticipatio mentis, but interpretatio naturae, mera experientia must guide him (Bacon). The human mind is and must be a tabula rasa, in qua nihil scriptum est, completely voraussetzungslos. Only then is knowledge reliable, if it is built up solely and exclusively from observation [152]. Begriffe ohne Anschauungen sind leer. The further man removes himself from experience and goes beyond it, the less he is to be trusted in his scientific striving. Therefore there is also no science possible of the supersensible (noumena) and of the supernatural. Metaphysica, theology, the spiritual sciences in general, even according to Comte psychology, are no science in the proper sense. Science is limited to the sciences exactes. And even within the circle of the observable phenomena our knowledge is limited to the that and how; the what and the why remains hidden. Cause and end, origin and destination of things lie beyond our reach; only the mutual relation of things, the relations invariables de succession et de similitude, A. Comte, Cours de philos. positive I p. 8 s. are the object of scientific investigation. Whether behind and above the observable phenomena there is still something else, whether the soul, God, the jenseits exists, may perhaps by another way, through practical reason, faith, fantasy etc. be able to be made plausible, but scientifically all that is and remains a terra incognita. The goal of science therefore can no longer lie in this, that one give a Welterklärung, but extends only to such a knowledge of reality, that we can thereafter arrange our life and draw practical benefit from it. Savoir, c'est prévoir; science, d'où prévoyance; prévoyance, d'où action. But this absolute bondage of the mind to the world of observation, has led others to the attempt, to explain not only the content of thought of the mind, but also consciousness and the mind itself from the world; empiricism has ended in materialism. Here too, therefore, progress,
history, development is to be noted. First the content of thought, then the faculty, finally also the substance of the mind is derived from the material world. E. Laas, Idealismus und Positivismus, 3 Bde 1879-84. Kuno Fischer,
Francis Bacon und seine Nachfolger, 2e Aufl. Leipzig 1875. A. Comte, Cours de philosophie positive, 2e ed. 1861-64. Die positive Philosophie von
A. Comte, im Auszuge von Jules Rig, übersetzt von J. H. von Kirchmann, Heidelberg, Weiss, 2 Bde. Littré, Aug. Comte et la philosophie positive,
Paris 1863. Id. Analyse raisonnée du Cours de philos. positive de M. A.
Comte, Utrecht, Kemink [153] 1845. J. Stuart Mill, Aug. Comte et le Positivisme, fransche vert. door Clémenceau, Paris 1868. Henri Taine, De l'intelligence, 2 vol. 3e ed. Paris, Hachette, 1878. l'Ange Huet, De methode der posit. filosofie, Leiden 1866. Id. New solution of an old question,
Leiden 1872. General foundations of the positive philosophy by A. Comte, 's Hage, 1846 (contains the first two lessons from Comte's work). Pünjer in Jahrb. f. prot. Theol. 1878 S. 79-121. 1882 S. 385-404. (Bibl. voor mod.
Theol. 1883 bl. 243 v). H. Gruber, A. Comte, der Begründer des Positivismus, Freiburg. Id. Der Positivismus von A. Comte bis auf unsere
Tage 1857-91, Freiburg 1891. Herzog2 art. Positivismus, van Zöckler. J.
Stuart Mill, System of Logic, ratiocinative and inductive, 2 Bde 9th ed.
Lond. 1875, duitsche vert. van Gomperz, 2e Aufl. Leipzig 1884. Opzoomer, The way of science, a handbook of logic 1851, 3rd revised printing under the title The essence of knowledge, a textbook of logic 1863. Id. Science and philosophy 1857. Id. The truth and its sources of knowledge 1859.
Pierson, Reflection, authority and experience 1855. Id. A view of life 1875 bl. 65 v. H. Spencer, A. system of synthetic philosophy, Vol. I First principles, 5th ed. Williams and Norgate, London 1887. F. A. Lange,
Geschichte des Materialismus, 4e Aufl. Iserlohn 1882. L. Büchner, Kraft und Stoff, 16e Aufl. Leipzig 1888 etc.
5. This empiricism does indeed have a powerful support in man's dependence on the nature surrounding him, but is nevertheless also burdened by weighty objections. In the first place it is certain that the spirit of man in his intellectual activity is never passive or even receptive in an absolute sense, but always also acts actively to a greater or lesser degree.
For it is not the eye that sees and the ear that hears, but man himself, who sees through the eye and hears through the ear. The simplest sensation and representation already presupposes consciousness, and thus an activity of the soul. Tabula rasa, on which the external world can write what it will, the human spirit never is; it is itself that perceives, connects the perceptions, compares, judges. But there is more; Kant, Kritik der reinen Vernunft,
Einleitung § 2 rightly says: Erfahrung lehrt uns zwar, dass etwas so oder so beschaffen sei, aber nicht, [154] dass es nicht anders sein könne. Now, however, we have not only particular and contingent, but also general and necessary truths, in logic, mathesis, etc., which the empiricists have in vain tried to derive from experience. The principle of causality e.g. has in truth been called the bulwark of the intuitive school; and all the effort that has been expended to explain this principle and foundation of all science from volition, from habit, etc. has been fruitless, Dr. G. Heijmans, Schets eener kritische gesch. van het causaliteitsbegrip in de nieuwere wijsbegeerte,
Leiden, Brill 1890. Dr. E. Koenig, Die Entwicklung des Causalproblems von Cartesius bis Kant, Leipzig, Wigand 1888. Spruyt, Proeve van eene geschiedenis van de leer der aangeboren begrippen, Leiden, Brill 1879. Yes, all sciences proceed from a series of unproved and unprovable propositions, which are assumed a priori and serve as a point of departure for all
reasoning and proof. Aristotle already saw this; there is no regressus in infinitum; precisely in order to have probative force, the proofs must finally rest in a proposition that needs no proof, that rests in itself, and that therefore can serve as ἀρχη ἀποδειξεως, principium argumentationis, Zeller,
Philos. der Gr. III 190 f. 235 f. Schopenhauer, Die Welt als Wille u.
Vorstellung, 6e Aufl. Leipzig 1887 I 78. A building cannot stand in the air, and a line of reasoning can rest only on a foundation that lies firm by evidence, and not by proof. The point of departure of empiricism is hereby judged, but also its conception of science is subject to serious objection. For it belongs to science by its nature to provide knowledge of the general, the necessary and eternal, the logical, the idea. Knowledge of phenomena, persons, facts, etc. is good, but is nevertheless only a preparatory labour; analysis should go before, but the synthesis must follow. Science exists only then, when we see through things in their cause and essence, in their goal and destination, when we know not only the ὁτι but also the διοτι and thus rerum dignoscimus causas. Empiricism, however, is compelled to deny to all sciences the name of science and to leave this only for the sciences exactes. But this limitation is impossible for a twofold reason. First because, besides, and then still [155] only in a certain sense, the purely formal sciences (logic, mathesis, mechanics, astronomy, chemistry) no science is possible without a philosophical element, and thus in every science discovery, intuition, imagination, i.e. in a word genius and in connection therewith the scientific hypothesis occupies a very weighty place. And secondly, because the name of science can then in the end be retained only for a few subsidiary disciplines, and precisely that knowledge which for man is the most important and for which he is concerned in investigation in the first place, is banished from the domain of science. It
nevertheless remains true, what following the example of Aristotle, Ethic.
10,7; de part. an. 1,5; de coelo et mundo 2,5. Thomas Aquinas said S.
Theol. I qu. 1 art. 5, ad. 1, Minimum quod potest haberi de cognitione rerum altissimarum, desiderabilius est quam certissima cognitio, quae habetur de minimis rebus. And Schopenhauer spoke in a similar spirit: Sie hören nicht auf, die Zuverlässigkeit und Gewissheit der Mathematik zu rühmen. Aber was hilft es mir, noch so gewiss und zuverlässig zu wissen, daran mir gar nichts gelegen ist, bij Van Oosterzee, voor Kerk en Theol. I 101. Moreover, the world of spiritual things, the Welt der Werthe, of good and evil, right and custom, religion and morality, of all that inspires us with love and hate, lifts us up and comforts or also casts down and pains, that whole rich invisible world is just as much for us a reality as the Welt der
Wirklichkeit, which we perceive with our senses. Its power over our life and in the history of mankind is much greater still than that of the visible things around us. One may then freely impose upon man the demand that he limit himself in his investigation because on this terrain no knowledge is possible; that demand rebounds upon what Schopenhauer has called das metaphysische Bedürfniss of the human spirit. Man is not only an intellectual but also a willing and feeling being; he is no thinking-machine but has, besides his head, also a heart, a world of emotions and passions.
These he brings with him in his scientific investigation; in his activity in study and laboratory he cannot exclude himself. It cannot be a demand that man in scientific labour, that is, in one of the noblest and highest activities of his spirit, impose silence upon his disposition, upon his heart, upon the best that is in him [156] and thus mutilate himself. This alone may always and thus also of the practitioner of science be demanded, that he be a good, a true man, a man of God, unto every good work, also unto this work of
science, suitably equipped (verg. boven bl. 29). If, however, one limits science both in a subjective and in an objective sense, one will obtain nothing else than that nevertheless along other paths provision for the metaphysical need is sought. Kant took the path of the practische Vernunft,
Comte introduced a service of humanity and devoted himself as high priest, Spencer bows down in humility before The Unknowable. All seek in one way or another, even into spiritism, magic, theosophy, compensation for what science does not grant them. And religion with all spiritual knowledge, first contemptuously driven out at the front door, is, but then many times in superstitious form, again admitted at the back door. Naturam expellas furcâ, tamen usque recurret. The inevitable consequence is then only this, that science is left undefended and unarmed to materialism. To that empiricism has in fact also led. If the content and presently also the intellectual faculty of the soul comes wholly and entirely from the external world, why then should not also the substance of the soul in the end be able to be explained from it? Over against this, however, there still stand the „sieben
Welträthsel" as a torment and an offence for materialistic thinking. The spiritual has not yet been explained from the material, just as little as rationalism has succeeded in deriving being from thinking. The transition between the two has not been found. Here is a chasm, which neither idealism nor materialism can bridge. It is even not rash to speak here not only of an Ignoramus but also of an Ignorabimus. But when we see how empiricism and rationalism, despite the great promises and the still greater expectations, in this century have ended in nothing other than materialism and illusionism, and in spite of their opposition have nevertheless promoted and assisted one another —the idealism of Hegel ended with Feuerbach and Strauss in materialism, and materialism with many investigators of nature
again passes over into half or whole idealism,— then in any case there is indeed reason to ask whether revision is not necessary of the whole [157] of modern philosophy, both in its Cartesian and in its Baconian direction; whether there are not other and better principia of science, which preserve us from both materialism and idealism? Schopenhauer, Die Welt als Wille und Vorstellung, 6e Aufl. 1887, I 505 f. II 192 f. E. v. Hartmann,
Naturwissenschaft u. Philosophie, Gesammelte Studien und Aufsätze, Berlin 1876, S. 421 f. E. L. Fischer, Die Grundfragen der
Erkenntnisstheorie, Mainz 1887, S. 314 f. Schmid, Erkenntnisslehre, Freiburg 1890 I 111 f. 243 f. II 13 f. Stöckl, Lehrb. der Philos. I 345 f.
Paulsen, Einl. in die Philos. 394 f. Strümpell, Einl. in die Philos. 75 f. W.
Dilthey, Einleitung in die Geisteswissenschaften, Leipzig, Duncker u.
Humblot 1883. Emil du Roys-Reymond, Uber die Grenzen des Naturerkennens. Die sieben Welträthsel. Leipzig, Veit u. C. 1882.
Pressensé, Les Origines, Paris Fischbacher 1883 p. 1-128. P. Vallet, Le Kantisme et le Positivisme, Paris 1887. Gretillat, Exposé de théol. systém. I p. 42 s. D. Chantepie de la Saussaye, Leven en Rigting 1865. Id. Empirisch of ethisch (Ernst en Vrede. 1858 bl. 193 v.) enz.
C. Realism.
6. The point of departure of epistemology ought to be ordinary, daily experience, the general and natural certainty of man concerning the objectivity and truth of his knowledge. For philosophy does not create the faculty of knowledge and knowing, but finds it and now attempts to explain it; and every solution which does not explain the faculty of knowledge but
destroys it, and does not understand knowing but makes it into an illusion, is thereby judged. Only such an epistemology has a chance of success, which on the one hand does not leave the ground of experience but on the other hand also penetrates into the whole depth of the problem, Prior homo, quam philosophus vel poeta, Tertull. de test. an 5. Primum vivere, deinde philosophari. Natural certainty is the indispensable foundation of science.
Scientific knowing is not a destruction but a purification, extension, completion of ordinary knowing, Kaftan, Die Wahrheit der Chr. Rel. Basel,
1889 S. 317 f. For every man assumes the reliability of the senses and the existence of the external world, not by a logical conclusion from the operation, in casu the representation [158] in his consciousness, to the cause outside himself, nor also by a reasoning from the resistance which his will experiences, to an objective reality which offers that resistance; but before all reflection and reasoning each is fully assured of the real existence of the world. This certainty is not born from a syllogism and rests on no proof, but is immediate, arising spontaneously in me with perception itself, not product but foundation and point of departure of all other certainty. Denn die ganze Welt der Reflexion ruht und wurzelt auf der anschaulichen Welt,
Schopenhauer, Welt als W. u. V. 6e Aufl. I 78. Only, in this connection, a distinction must indeed be made between the certainty which is at once given with the actual perception of an object, and that which later, after the perception has long since passed, follows from the representation that has remained behind. Only the first is treated of here, and this is not a conclusion from a reasoning, but is immediately present in me with perception itself. Cf. Ed. Zeller, Ueber die Gründe unseres Glaubens an die
Realität der Aussenwelt 1884. E. L. Fischer, Die Grundfragen der Erkenntnisstheorie 1887 S. 392 f. Paulsen, Einl. in die Philos. 385 f. Flügel,
Die Probleme der Philosophie und ihre Lösungen, Cöthen, Schulze, 2e Aufl. 1888 S. 104 f. Schmid, Erkenntnisslehre 1890 II 307 f. Land, Inl. tot de wijsbeg. bl. 97 v. enz.
7. This one fact already, the natural certainty concerning the reliability of the senses and the reality of the external world, proves that there exists yet another certainty than scientific, demonstrative certainty. The empiricists have wrongly denied this. Experience teaches only that something is, but not that it must be, teaches us only the contingent, the changeable, makes reality known to us. We, however, also have general, necessary truths, of which we are certain not by observation and reasoning, but a priori. Most philosophers have therefore, alongside the scientific or mediate, also assumed a metaphysical, intuitive, immediate certainty, also called a certainty of faith, of evidence. Aristotle was the first clearly to see that the ἐπιστημη in the last instance is built upon unprovable, evident truths. Some, such as Plato, Cartesius, Leibniz, Rosmini, have sought to explain this unchangeable, eternal character of truth by [159] the doctrine of innate ideas, cf. Spruyt, Proeve van eene gesch. van de leer der aangeb. begrippen,
Leiden 1879. But this doctrine rests on an untenable dualism of subject and object, makes the human spirit independent of the cosmos, is in principle rationalistic and leads logically and also historically to absolute idealism.
This was the reason why the doctrine of the ideae innatae was unanimously rejected by the scholastic and also by the Reformed theologians, Spruyt ib.
57-60. Frohschammer, Die Philosophie des Thomas von Aquino, Leipzig, Brockhaus 1889 S. 44 f. Liberatore, Die Erkenntnisstheorie des H. Thomas v. Aquin, deutsch von Eugen Franz, Mainz 1861 S. 130 f. Polanus, Synt.
Theol. p. 325. Zanchius, Opera III 636 sq. Voetius combats the doctrine of Cartesius expressly in his Disput. Sel. V 477-525. They even adopted the
empiricist proposition: nihil est in intellectu quod non prius fuerit in sensu, and spoke of the human being before he perceives as of a tabula rasa, in qua nihil scriptum est, Thomas S. Theol. I qu. 79 art. 2. Voetius, Disp. V 459,
525. And they maintained this, because the human being, in distinction from the angels, is bodily, his body is not a prison but belongs to his nature and he is through that body bound to the cosmos, Thomas ib. I qu. 84 art. 3. qu. 85 art. 1. Voetius ib. V 483. They have thus on the one hand rejected rationalism as decisively as possible, not only in the form of the innate concepts, in which it was taught by Plato, Cartesius, Leibniz, but also in that of the innate forms, in which it appeared with Kant, and in that of the innate idea of being, in which it emerged with Rosmini and the ontologists.
But on the other hand the above-mentioned expressions nevertheless may not be understood in the sense of Locke's empiricism. If Thomas calls the human spirit a tabula rasa, then he by no means intends thereby to deny that nevertheless ipse intellectus is innate to him. Leibniz added to the maxim nihil est in intellectu quod non prius fuerit in sensu, the restriction nisi ipse intellectus. Thomas expresses himself still more precisely: species aliorum intelligibilium non sunt ei innatae, sed essentia sua sibi innata est, ut non eam necesse habeat a phantasmatibus acquirere, qu. de mente art. 8 ad 1 cf.
Liberatore, ib. 144. And Voetius explains the above-mentioned maxim thus, that thereby it is not excluded that the intellect in the sensibly perceived world [160] can also notice and know the eternal and unchangeable, e.g. in the works of nature also their author, namely God. And this is then also the proper thought of their Erkenntnisstheorie: the human spirit is not able and in any case not in the position, outside the sensible world, out of its own fund, with its own means, to bring forth the knowledge of things, not even the knowledge of the principia aeterna, κοιναι ἐννοιαι. It is from the outset
bound to the body and thereby to the cosmos, and therefore the intellectus too can come to no activity except through and on the basis of the sensus.
The intellectus is at the beginning pure potentia, tabula rasa, without any content, and is first from without by the sensible world awakened to activity, to actuality. The impulse thus proceeds from the sensible world; this acts upon the human spirit, rouses it awake, and urges it to action. But as soon as the intellectus begins to work, it at once and of itself also works in its own way and according to its own nature. And the nature of the intellectus consists in this, that it possesses the vis, facultas, inclinatio, aptitudo, in and with perception at once, of itself, involuntarily, sine ullo labore, sine praevio studio, sine ratiocinatione to form those basic concepts and basic principles which stand firm a priori, before every reasoning and before all proof, and therefore deserve to be called veritates aeternae. Thus thinking itself, as soon as it begins to work, of itself feels itself bound to the laws of thought; in thinking itself the laws of thought lie enclosed and come to light. Thus experience teaches us what a part and what a whole is, but the intellect at once understands that a whole is greater than its part. Thus experience teaches us what is good and what is evil, but the intellectus practicus knows immediately that the one must be done and the other must be omitted. This does not mean that every human being can now also give clear account to himself or others of these basic concepts and basic principles; but every human being, even the simplest, nevertheless applies these basic concepts and basic principles, without any scientific reflection, unconsciously and with the greatest certainty in life. The difference between this doctrine of the faculty of knowledge and that of rationalism and empiricism lies in these two: first, in a peculiar conception of the intellectus, which brings with it a proper nature and correspondingly [161]
also begins to work in a proper way, and second, in this, that this intellectus, thus working according to its own nature, nevertheless does nothing other than abstract that logical element from the perceived things, which by nature also lies hidden in those things. Rationalism, as it were, compels the things to conform to the intellect, fits them into forms of which it does not know whether they fit them, constructs the world according to a play of concepts. Empiricism compels the spirit to conform to the sensible world, clips it in its ideal flight, and finally explains it itself out of matter. But the Erkenntnisstheorie, which has gradually arisen in Christian theology and in its main lines was first conceived by Augustine, maintains both, the freedom and the boundness of the human spirit; the freedom to ascend to the world of the ideal, the boundness by which it also in this its flight does not lose the world of reality from under its feet.
8. The point of departure of all knowledge in man is therefore senseperception. Οὐδε νοει ὁ νους τα ἐκτος μη μετ' αἰσθησεως ὀντα, Arist. de sensu c. 6, Zeller Philos. d. Gr. III 198. All intellectual cognition begins from sense, Thomas S. Theol. I. qu. 84 art. 1 en 7. Our intellect understands nothing without a phantasm, id. C. Gent. III 41. And all Christian theologians were of the same thought. The error of scholasticism, among Protestants as well as Roman Catholics, lay only in this, that it was finished with observation far too early and thought it had been almost completely, in every field of science, taken up and laid down in the books of Euclid,
Aristotle, the church fathers, the confession. In that opinion one neglected observation and began at once with the concepts already obtained, Spruyt,
Proeve 36. Therefore it could almost be called a discovery, when Bacon returned to sense-perception as to the only source of knowledge. Yet it was no discovery, but indeed a necessary refreshment for science, for this must
always return again to the sources. Not from books, but from the real world must truth be drawn. Intuition is the source of all genuine science. Die
Anschauungen sind die Kontanten, die Begriffe die Zettel, Schopenhauer, Die Welt u. s. w. 6e Aufl. II 76 cf. 76-98. Now in this sense-perception each
[162] sense has its own nature and its own task; each seeks out in the phenomena what is akin; the sense of touch makes known to us the mechanical, taste and smell make known to us the chemical properties, hearing opens to us the world of tones and sight that of colors, Arist. bij
Zeller, Philos. d. Gr. III 533 f. Thomas, S. Theol. I qu. 78 art. 3.
Schopenhauer, Die Welt u. s. w. II 30-36. Land, Inleiding 63 v. Bilderdijk, Taal-en Dichtk. Verscheidenheden, 1821 II 39 v. Verhandelingen, ziel-, zedeen rechtsleer betreffende 1821 bl. 12 v. Brieven V 48. The senses therefore each by itself do not perceive the whole object, but only certain properties of that object. The perceptual image that arises in our consciousness is composed of many different impressions, which, received by the different senses, transmitted along the nerve fibers into our brains, there in an inexplicable way converted into sensations, and connected into a whole. There are no simple sensations; they are all already composed out of various others; every object that we see, every tone that we hear is already a complex of perceptions. The human mind is therefore already active in the simplest perceptions; it is no tabula rasa, on which the external world merely writes what it will, no mirror, in which the object is simply reflected. But every perceptual image is formed in consciousness itself out of the factors that are supplied from the object by the different senses.
Therefore the question is of such great importance, what the relation is between the perceptual image, the representation (φαντασια, φαντασμα, species sensibilis, perception, Vorstellung) in our consciousness and reality,
the object, outside us. Greek philosophy in general proceeded from the thought that like could only be known by like; φασι γαρ γιγνωσκεσθαι το ὁμοιον τῳ ὁμοιῳ, Arist. de an. I 2. Some inferred from that that the soul of man had to consist of the same elements and atoms as the real world, and that in perception material atoms from the objects penetrated into the soul.
Aristotle, however, understood this thus, that the soul is not actually but potentially all that is thought —ἡ ψυχη τα ὀντα πως ἐστι παντα, de an. III,
8— and that the objects by perception and thinking acquired an ideal existence in the soul. Scholasticism adopted this and [163] said: the known is in the knower according to the mode of knowing, not according to the mode of the known, i.e. the things themselves do not pass over into the soul, but only their image, their form, εἰδος, forma, species, similitudo,
Thomas S. Theol. I qu. 75. I 2 qu. 5 art. 5. II 2 qu. 23 art. 6 ad 1. S. c. Gent.
I 77 II 77, 98. There is therefore on the one hand an essential difference between the thing and its representation, for the former is outside us, has there a real existence, but the latter exists in us and has only an ideal existence. But on the other hand there was nevertheless also a complete correspondence; the representation is an image, a faithful ideal reproduction of the object outside us. Modern philosophy, however, attending to the activity of man's consciousness in the forming of perceptual images, has dug an ever wider gulf between thing and representation. The perceptual images are no species, formae, but at most still signs, symbols, diagrams of the external world, freely formed in our mind on the occasion of the modifications that are brought about from without through the senses and nerves into our brain cells. If this is so, the objective world disappears ever further from our sight; it dissolves into appearance; for a checking of the perceptual image against reality is therefore impossible, since we can never
approach it, and the perceptual image always inserts itself between it and us, Land, Inleiding 71, and the earlier cited litt. The error that underlies this theory seems to be this, that the proper object of our perception would not be the thing outside us, but some impression or vibration of our nerves in us. Now it is certainly true that no representation can be formed in our consciousness without vibrations being transmitted in the nerves to our brain cells. But neither the image that is cast on the retina of the eye, nor the modifications in the brain cells as a result of the nerve vibrations are the cause from which the sensation and representation in our consciousness arises. All psychometric investigations, however important, have not brought us one step nearer toward an explanation of this wondrous phenomenon. We stand here before a, as it seems, insoluble riddle. The nerve vibrations can be traced into the center of the brain; their strength and speed can be calculated; [164] but the representation that thereafter arises in our consciousness is toto genere different from that. It is a psychic, spiritual act, never to be explained from physical phenomena, such as the nerve vibrations are. Thus the representations cannot be products that are produced in our consciousness by the nerve vibrations, ourselves unconscious of it. And they also cannot be conscious creations of our mind, on the occasion of the modifications in our brain cells, for the simple reason that no one knows anything at all of this whole process of nerve vibrations in perception, and only by deliberate physiological investigation acquires knowledge of it. In addition, the nerve vibrations and modifications in the brain cells sometimes indeed, in seeing without noticing, in hearing without understanding, etc. proceed wholly and purely mechanically, but that they nevertheless in actual perceiving are always already accompanied by a psychic act. It does not go so that the nerve vibrations are first transmitted
into our brains, and that only thereafter consciousness awakens and forms the representation out of those modifications in the brain cells; but perception itself through the senses is an act of consciousness. It is the spirit of man that sees through the eye and hears through the ear. The object of perception is therefore not any phenomenon in me, but the thing outside me. The same spirit that sees the object is also the one that forms the representation. Both are psychic acts. Therefore there is also no reason to doubt that in the representations we have a faithful, ideal reproduction of the objects outside us. In that connection it is to a certain extent immaterial whether we call the representations εἶδη, species, formae, signs, symbols, etc. of the things; for these words too are images, and for the most part borrowed from visual perception. Provided only that it stands firm that the representations in their whole and in their parts are faithful interpretations of the world of reality outside us.
9. But the human spirit does not stop with these representations. Scientific knowledge does not arise from the senses but from the intellect. Not mere observation, but serious reflection on the observed phenomena have made
Copernicus the father of astronomy and Newton the [165] discoverer of gravitation. The observation of phenomena is necessary and good, but it is not the only and the highest. The object of science is not the particular but the universal, the logical, the idea. Greek philosophy had already seen this.
Socrates was the first who, with consciousness, conceived the idea of knowing and made it the principle of his philosophy; science is knowledge, not of appearance, but of the essence of things, Xenophon, Memor. IV, 6.1.
Plato distinguished between δοξα, which had as its content ordinary, empirical knowledge, and ἐπιστημη, which had as its content the truly being of things, Rep. V 476 D-478 D. Sympos. 202 A etc. And Aristotle
defined science in the same sense as knowledge του ὀντος, του καθολου, των πρωτων αἰτιων και ἀρχων (places in Zeller, Philos. d. Gr. III 161 f).
Augustine in particular placed this intellectual knowledge in the foreground. He does not reject knowledge through the senses, he defends its truth against the Academici in a separate writing, and acknowledges that we understand the invisibilia Dei per ea quae facta sunt, de Gen. ad. litt. 4,32.
But he nevertheless undervalues its worth, like Plato; the sensible yields only δοξα, c. Acad. 3,26, it is not the truth itself, it is only an image of it,
Solil. 2,32. Knowledge of nature is without value, nihil prodest, Conf. 5,7.
10,55. Enchir. 3,5. There are really only two things that it is important to know, God and ourselves: deum et animam scire cupio. Nihilne plus? Nihil omnino, Solil. 1,7. And he obtains this knowledge not by looking outward, but by looking inward; noli foras ire, in te ipsum redi, in interiore homine habitat veritas, de vera relig. c. 39 n. 72; not by sensible observation but by thinking; aliud est sentire, aliud nosse, de ord. 2,5. cf. Solil. 2,33.
Scholasticism, attaching itself more closely to Aristotle, has better seen the value of sensible observation, but has nevertheless also fully acknowledged the significance of the intellectus for science. Thomas expressed this briefly and clearly as follows, scientia non est singularium, S. Theol. I qu. 1 art. 2, intellectus est universalium, S. c. Gent. I c. 44. Science has as its object the universal and necessary, S. Theol. I qu. 14 art. 13 ad 3. I qu. 84 art. 1 ad 2. I qu. 86 art. 1 en 3, and can therefore be provided only by the intellectus. For while sensible [166] observation considers things quantum ad exteriora ejus accidentia, it is precisely the distinctive feature of the intellectus that it penetrates ad interiora rei, S. c. Gent. I 58. III 56. IV 11, penetrat ad essentiam rei, S. Theol. II. 2 qu. 8 art. 1. Its proper object is the quidditas rei materialis, S. Theol. I qu. 85 art. 5 ad 3. The intellect, namely, as intellectus
agens, that is, as a power of abstraction, as we would call it, separates the universal from the sensible representations; it lets the particular fall away from them, it shines over them as a light, makes them intelligible, lets the universal become knowable from them, and then, as intellectus possibilis, i.e. as an intellectual cognitive faculty, takes that universal into itself and makes it the property of the spirit, S. Theol. I qu. 79 art. 3 en 4. I qu. 84 art.
6. S. c. Gent. II 76.77. III 45.
Now in fact there is as yet no difference on this point, that not sensible perception but the understanding is the organ of science. Empiricism too has not denied this. Bacon, Hume, St. Mill fully acknowledge that sensible perception is indeed the first but not the only thing and that the understanding by induction seeks to derive the general from the particular.
Bacon was concerned precisely with a reliable method, according to which from particular observations generally valid judgments could be formed.
But with the concepts which the understanding forms from the representations, the question returns with double seriousness, which above was already asked with the perceptual images: what is the relation between these concepts of the understanding and the world of reality? And here
Nominalism and Realism diverge. Both directions occur in the essence of the matter already in Greek philosophy. Plato and Aristotle were realists, be it also with distinction; and the actual thought of nominalism we find already, inter alia, in the Cynic philosopher Antisthenes, who denied the reality of the general concepts and said against Plato: ἱππον μεν ὁρῶ, ἱπποτητα δε οὐχ ὁρω, Zeller, Philos. der Gr. II4 295, and in the Stoic philosophers, who held the ἐννοηματα, the thoughts, only for φαντασματα διανοιας, ib. IV3 79. 125. In the Middle Ages this view of the general concepts was renewed and it received the name of nominalism. Roscellinus
was of the opinion that the general concepts were only flatus vocis, thoughtthings, [167] to which no reality corresponds; in reality there are no general but only particular, individual things, there is no humanity but there are only human beings etc. The struggle between realism and nominalism continued until the 15th century. Cf. A. Stöckl, Gesch. der Philos. des
Mittelalters. 3 Bde Mainz 1864-66 I 135 f. II 986 f. Hauréau, De la philosophie scolastique, 2 vol. Paris 1850. Schwane, Dogmengeschichte der mittl. Zeit. Freiburg 1882 S. 4 f. Furthermore history of the dogmas by Bach, Thomasius, Münscher, Baur, Harnack etc., hist. of philos. by Ueberweg, Erdmann, Windelband etc. A. Pierson, De realismo et nominalismo 1855. Id. Hist. of the R.-Catholic. III 1871 p. 53 v. 87 v. 183 v.
Spruyt, Proeve 66 v. But even after that the question has not departed from philosophy. The dispute between realism and nominalism is not a point of contention of scholastic subtlety, but of deep-reaching significance.
Nominalism has appeared again in newer form as empiricism in modern philosophy, Spruyt, Proeve passim. Hugo Spitzer, Nominalismus und
Realismus in der neuesten deutschen Philosophie mit Berücksichtigung ihres Verhältnisses zur modernen Naturwissenschaft. Leipzig 1876. Janet,
Traité élémentaire de philos. Paris, Delagrave 1887 p. 162 s. Land, Inleiding 107 v. Pierson, Wijsgeerig Onderzoek. Deventer, ter Gunne 1882 p. 200 v. If now nominalism has the right on its side, it is the end of all science. For one of two: if we can summarize the corresponding characteristics of a group of things in a concept and word, then this happens either without ground and those words and concepts represent no value in reality; or the things resemble one another in reality and have common characteristics. In this case, however, the concepts are not empty thoughtthings, but the sum of essential properties of the things, and thus not nomina
but res. Therefore realism too without doubt was right, when it assumed the reality of the general concepts, not in a Platonic or ontological sense ante rem, but in an Aristotelian sense in re, and therefore also in mente hominis post rem. The general, which we express in the concept, does not exist precisely thus, as universale, outside us (cf. above p. 23); but in each specimen of the species particularly individualized and specialized, it nevertheless has its ground in the things and is abstracted from them by the activity of the understanding and expressed in a concept, Thomas, S. Theol.
I qu. 85 art. 2 ad 2. S. c. Gent. I 65. With the concepts we therefore do not remove ourselves from reality, but approach it more and more. It does indeed seem that we, forming concepts and judgments and conclusions, more and more lose the firm ground under the building of our knowledge and float high in the air. It seems strange and wonderful that we, converting the representations into concepts and then again processing these according to the laws of thinking, obtain results that are in agreement with reality. And yet whoever gives up this conviction is lost, Land, Inleiding p. 250. But that conviction can then also rest only in the faith that it is one and the same
Logos that created both the reality outside us and the laws of thinking within us, and that set both in organic connection with and let them correspond to each other. Thus alone is science possible, i.e. knowledge not only of the changing appearance but of the general, of the logical in things.
Certainly, the being itself of things, their existence, remains outside us; never do the things themselves realiter enter into us; being is therefore never to be approached by us, it is a factum that must be accepted and that constitutes the foundation of thinking. But insofar as things also exist logically, have proceeded from thought and rest in thought Joh. 1:3, Col.
1:15, they are also comprehensible and thinkable for the human spirit.
10. Plato clarified this process of science by means of a beautiful and striking image. Just as the sun objectively illuminates the object and subjectively our eye, so God or the idea of the good is the light by which the truth, the being of things, becomes visible and at the same time our mind can behold and acknowledge that truth, cf. Siebeck, Geschichte der
Psychologie, I Theil, 2 Abth. Gotha, Perthes 1880, '84 I 226. Aristotle, ib. II 70. Augustine adopted this image: God is the sun of minds. In the unchangeable light of truth our mind sees and judges about everything, in ipsa incommutabili veritate mens rationalis et intellectualis intuetur, eaque luce de his omnibus judicat, de Gen. ad litt. L. 8 cap. 25. Just as we with the bodily eye [169] can see nothing if the sun does not spread its light over it, so we also can see no truth except in the light of God, who is the sun of our knowledge, Solil. I c. 8, 13, de Trin. 12 c. 15. Deus intelligibilis lux, in quo et a quo et per quem intelligibiliter lucent, quae intelligibiliter lucent omnia.
Thomas speaks repeatedly in the same way, and employs the same comparison, S. Theol. I qu. 12 art. 11 ad 3, qu. 79 art. 4, qu. 88 art. 3 ad 1.
II 1 qu. 109 art. 1 ad 2. S. c. Gent. 3 c. 47. Only Thomas pointed out that this must not be understood pantheistically, as Averroes taught under Neoplatonic influence and in this was later followed by Malebranche and the ontologistic school. Just as we, says Thomas, in natural seeing, not by ourselves being in the sun, but by the light of the sun that shines upon us, so we also do not see things in the divine essence, but by the light that from God shines in our own intellectus. Reason in us is that divine light; it is not the divine logos itself, but has a share in it. To God belongs the esse, vivere, intelligere per essentiam, to us per participationem S. Theol. I qu. 79 art. 4.
This image of the sun led to speaking, in a sound sense, of the natural light of reason, cf. Polanus Synt. Theol. p. 325. Zanchius, Opera III 636 sq.,
under which then nothing else was understood than that permanent property or power of the human mind by which it is enabled, immediately upon the first observations, to form those basic concepts and basic principles which further guide it in all observation and thinking. The light of reason is thus in the first place similar to the intellectus agens, to the power of abstraction, which shines over the objects and causes the intelligibile to come forth from them, and further to that fund of κοιναι ἐννοιαι, which our mind makes its own precisely through the power of abstraction. But in both senses that light is to be ascribed to God, or more specifically to the Logos, Ps. 36 vs. 10,
Joh. 1:9. He is the one who causes this light to arise in us and continually maintains it. And thus it is not to man, who is only an instrument, but to God that it is to be ascribed, if through the rays of that light the truth reveals itself to our mind, Liberatore, Die Erkenntnisslehre des h. Thomas v. A. 185 f. Kleutgen, Die Philosophie der Vorzeit, 2e Aufl. Innsbrück 1878 I 89 f.
[170] This beautiful metaphor makes clear to us what the principia are from which all science proceeds. Not only in theology, as the previous § showed us, but in every science there are three principia to be distinguished. Here too God is the principium essendi; in his self-consciousness lie the ideas of all things; all things rest on thoughts and have been created by the word.
But it is his good pleasure to transfer from this cognitio archetypa in his divine consciousness an ectypal knowledge into man, who has been made after his image. But he does that, not by letting us behold the ideas in his essentia (Malebranche), nor also by giving them all to us already at birth
(Plato, doctrine of the ideae innatae), but by spreading them out in the works of his hands before the spirit of man. The world is an embodiment of God's thoughts; it is a beautiful book, in which all creatures, great and
small, are as letters, which give us to behold the invisible things of God; it is no writing-book, in which, according to the representation of the idealists, we would have to fill in the words, but a reading-book, from which God makes known to us what he has written down in it for us. The created world is thus the principium cognoscendi externum of all science.
But that is not enough. In order to see, an eye is necessary. Wär' nicht das Auge sonnenhaft, wie könnten wir das Licht erblicken? There must be correspondence, affinity, between object and subject. The same Logos, which shines in the world, must also let his light shine in our consciousness.
That is the intellectus, the ratio, which, itself derived from the Logos, discovers and recognizes the Logos in things. It is the principium cognoscendi internum. Sicut scientia in nobis est sigillatio rerum in animabus nostris, ita e converso formae non sunt nisi quaedam sigillatio divinae scientiae in rebus, Thomas, bij Liberatore, Die Erkenntnisstheorie des h. Thomas v. Aq. S. 148. Thus it is then God alone, who out of his divine consciousness brings in the knowledge of the truth through the creatures into our spirit; the Father, who through the Son in the Spirit reveals himself to us. Multi dicunt: quis ostendet nobis bona? Signatum est super nos lumen vultus tui, Domine! [171]