127. And here we would remark how profound a philosopher St. Thomas shows himself to be, when he explains the manner in which God knows his creatures. In his _Summa Theologica_,[7] he asks if God knows things distinct from himself, and answers in the affirmative; not that he regards the divine essence as a mirror, but that by recourse to a more profound consideration he seeks the origin of this knowledge in causality. This is his doctrine in a few words: It is manifest that God knows himself perfectly; therefore he knows all his power, and consequently all the things to which it extends. Another reason, or rather enlargement of the same reason, is, that the being of the first cause is its intellect: all effects pre-exist in God as in their cause; they must, therefore, be in him in an intelligible manner, since they are his intellect itself. God then sees himself by his essence; but he sees other things not in themselves, but in his essence, inasmuch as his essence contains the similitude of everything. [7] P. 1^a, Q. 14^a, A. 5^o. The same doctrine is found in another place,[8] where he asks if they who see the divine essence see all things in God. [8] Q. 12^a, A. 8^o. 128. Representation of ideality is that which neither proceeds from the identity of the thing representing with that represented, nor from the relation of cause and effect. Our ideas are of this class, for they are neither identical with their objects nor do they cause them. It is impossible for us to know whether, besides this representative force which we experience in our ideas, there are finite substances capable of representing things distinct from, and not caused by, themselves. Leibnitz maintains that there are such substances; but, as we have seen, his system of monads must be regarded as merely hypothetical. It is better to say nothing than to make conjectures which lead to no result; we shall therefore content ourselves with establishing the following propositions: I. If any being represent another which is not its effect, it has not this representative force of itself, but has received it from another. II. The communication of intelligences can only be explained by recurring to a first intelligence, which, being the cause of the others, can give them the force to act upon one another, and consequently to produce representation. 129. Causality may be a principle, but is not a sufficient reason, of representation. In the first place, a cause cannot represent its effect unless intelligible in itself. Thus, although we attribute to matter an activity of its own, we cannot concede it the power to represent its effects, for want of the indispensable condition of immediate intelligibility.