The solution of the third antinomy, the subject of which was the Idea of freedom, deserves a special consideration, because it is for us very well worth notice that it is just here in connection with the Idea of freedom that Kant is obliged to speak more fully of the thing in itself, which was hitherto only seen in the background. This is very explicable to us since we have recognised the thing in itself as the will. Speaking generally, this is the point at which the Kantian philosophy leads to mine, or at which mine springs out of his as its parent stem. One will be convinced of this if one reads with attention pp. 536 and 537; V. 564 and 565, of the "Critique of Pure Reason," and, further, compares these passages with the introduction to the "Critique of Judgment," pp. xviii. and xix. of the third edition, or p. 13 of Rosenkranz's edition, where indeed it is said: "The conception of freedom can in its object (that is then the will) present to the mind a thing in itself, but not in perception; the conception of nature, on the other hand, can present its object to the mind in perception, but not as a thing in itself." But specially let any one read concerning the solution of the antinomies the fifty-third paragraph of the Prolegomena, and then honestly answer the question whether all that is said there does not sound like a riddle to which my doctrine is the answer. Kant never completed his thought; I have merely carried out his work. Accordingly, what Kant says only of the human phenomenon I have extended to all phenomena in general, as differing from the human phenomenon only in degree, that their true being is something absolutely free, i.e., a will. It appears from my work how fruitful this insight is in connection with Kant's doctrine of the ideality of space, time, and causality.
Kant has nowhere made the thing in itself the subject of a special exposition or distinct deduction; but, when ever he wants it, he introduces it at once by means of the conclusion that the phenomenon, thus the visible world,
