91. The German philosopher further says: "This subjective condition of all knowledge cannot with propriety be converted into a condition of the possibility of a knowledge of the objects; that is, into a conception of thinking being in general, since we cannot represent this being to ourselves without putting ourselves in its place by the formula of our consciousness." I do not believe that the psychologists who have pretended that they could demonstrate the simplicity of the soul, ever flattered themselves with arriving at a perfect idea of thinking beings, or denied that we obtain the type of this idea from our own experience; what they have pretended is, that reason leads them to infer that there is absolute unity of the subject wherever there is a thinking being; whether its thought may belong to a higher or lower order than our own.
92. When Kant observes that the subject in which the thought inheres is only indicated in a transcendental way, without its properties being discovered, and that, therefore, we do not know the simplicity of the subject itself, he declares a fact which is in some sense admissible, but he deduces from it a false consequence. It is true that we only know the substance of the soul by the presence of the internal sense, and by its relation to its acts; and consequently that the soul in itself abstracted from all the phenomena which we experience, is not given in immediate intuitions, and that when we arrive at this point we are reduced to the idea of a simple being, but this indeterminateness, and vagueness, in the knowledge of the substance of the soul, does not prevent our knowing its simplicity, if this simplicity is revealed by the internal sense, and also by the nature of the phenomena by which we know the thinking subject.
93. Some persons may believe that the indeterminateness of the knowledge of the substance of the soul is a fact recently discovered by the German philosopher; but it is easy to show that it had been observed long before, and is laid down in a very special and interesting manner in the writings of St. Thomas. This eminent metaphysician proposes the question whether the intellectual soul knows itself by its essence, utrum anima intellectiva seipsam cognoscat per suam essentiam, and after the various remarks on intelligence, and the intelligibility of objects, he solves it in these remarkable words: "Our understanding does not know itself by its essence, but by its act; and this in two ways: in one way, in particular; inasmuch as Sortes or Plato perceives that he has an intellectual soul, because he perceives that he understands: in the second way, in general; inasmuch as we consider the nature of the human mind in the act of the understanding. But it is true that we derive the judgment and efficacy of the knowledge by which we know the nature of the soul, by the light of the divine truth of which our intellect participates, and in which are contained the reasons of all things, as was said above. Hence, Augustine says, in the ninth book on the Trinity: We have intuition of the inviolable truth by which we perfectly determine, as far as possible, not what the mind of each man is, but what it should be according to the eternal reasons. But there is a difference between these two cognitions, for, to have the first, we only need the presence of the mind, which is the principle of the act by which the mind perceives itself, and, therefore, we say that it knows itself by its presence; but for the second, the presence of the mind is not sufficient, but a careful and subtile investigation is necessary. Hence many are ignorant of the nature of the soul, and many also have erred on the nature of the soul; wherefore in the tenth book on the Trinity, Augustine, speaking of this investigation, says: The soul should not try to see itself as something absent, but endeavor to distinguish itself as something present; that is, to know its difference from other things, which is to know its quiddity and nature."[49]
94. It is to be observed that St. Thomas admits two cognitions of the soul by itself;—that of its presence, as we perceive it in perceiving our thought, percipit se habere animam intellectivam ex hoc quod percipit se intelligere; and another which we deduce from the analysis of the intellectual act reasoning from general considerations, and reflecting on the light which the eternal reasons shed upon this fact of experience. This is how St. Thomas explains the knowledge of presence or consciousness contained in the proposition, I think; and the general knowledge which we deduce from the same intellectual act in its relations to the unity of the subject exercising it. That this last contains something abstract and indeterminate no one denies; and when Kant calls attention to it, he tells us nothing which the holy Doctor had not already told us when he expressly affirmed that the soul knows itself not in its essence, but in its acts. These few laconic words express all the truth which is contained in Kant's diffuse explanation of the limitation of our cognition to the acts of consciousness, and the absence of the intuitive knowledge of the substance of the soul, the transcendental subject of the thought.
[CHAPTER XIII.]
IN WHAT MANNER THE IDEA OF SUBSTANCE MAY BE APPLIED TO GOD.
95. In the idea of substance as formed from the beings around us and from the testimony of our consciousness we find the relation to changes which occur in it as their subject or recipient. But we have before remarked that besides this relation there is a negation of inherence in another as the modifications are inherent in the substance; this negation implies a perfection which exempts it from the necessity of inherence to which the changeable and transitory beings which we call accidents or modifications are subject. As we are ignorant of the intrinsic essence of substances, we do not know what this perfection is; yet we cannot doubt that it exists in the very nature of the subject, and is independent of the modifications which transform it. If then the essence of the substance must consist in any thing, it must be in this perfection of which we have a knowledge, but not an intuitive cognition. When therefore substance is defined in relation to accidents, quod substat accidentibus, it is rather defined by the manner in which it is presented to us than by what it is in itself.
96. Hence, of the two definitions usually received in the schools: Ens per se subsistens, a being subsisting by itself, and, id quod substat accidentibus, the subject of accidents; the first is the more correct, because it comes nearer the expression of what it is in itself. Although we know finite substances only inasmuch as revealed by accidents, and even our own mind knows itself only in its acts, reason tells us that in order to be known things must exist, and in order that our mind may find in them something permanent, it is necessary that this something should be in them. Our knowledge does not produce its objects; in order to be known they must exist.