Men followed the words,—such words as “_a priori_ ideas,” “forms of perception and thought existing in consciousness independently of experience,” “fundamental conceptions of the pure understanding,” &c., &c.,—and asked whether Plato’s Ideas, which were also original conceptions, and besides this were supposed to be reminiscences of a perception before life of the truly real things, were in some way the same as Kant’s forms of perception and thought, which lie _a priori_ in our consciousness. On account of some slight resemblance in the expression of these two entirely different doctrines, the Kantian doctrine of the forms which limit the knowledge of the individual to the phenomenon, and the Platonic doctrine of Ideas, the knowledge of which these very forms expressly deny, these so far diametrically opposed doctrines were carefully compared, and men deliberated and disputed as to whether they were identical, found at last that they were not the same, and concluded that Plato’s doctrine of Ideas and Kant’s “Critique of Reason” had nothing in common. But enough of this.(45) § 32. It follows from our consideration of the subject, that, for us, Idea and thing-in-itself are not entirely one and the same, in spite of the inner agreement between Kant and Plato, and the identity of the aim they had before them, or the conception of the world which roused them and led them to philosophise. The Idea is for us rather the direct, and therefore adequate, objectivity of the thing-in-itself, which is, however, itself the _will_—the will as not yet objectified, not yet become idea. For the thing-in-itself must, even according to Kant, be free from all the forms connected with knowing as such; and it is merely an error on his part (as is shown in the Appendix) that he did not count among these forms, before all others, that of being object for a subject, for it is the first and most universal form of all phenomena, _i.e._, of all idea; he should therefore have distinctly denied objective existence to his thing-in-itself, which would have saved him from a great inconsistency that was soon discovered. The Platonic Idea, on the other hand, is necessarily object, something known, an idea, and in that respect is different from the thing-in-itself, but in that respect only. It has merely laid aside the subordinate forms of the phenomenon, all of which we include in the principle of sufficient reason, or rather it has not yet assumed them; but it has retained the first and most universal form, that of the idea in general, the form of being object for a subject. It is the forms which are subordinate to this (whose general expression is the principle of sufficient reason) that multiply the Idea in particular transitory individuals, whose number is a matter of complete indifference to the Idea. The principle of sufficient reason is thus again the form into which the Idea enters when it appears in the knowledge of the subject as individual.