for thus alone can they make possible a cognition of a quite supersensible Being. — The only concept of this kind to be met with in human Reason is that of the freedom of men under moral laws, along with the final purpose which Reason prescribes by these laws.

Of these two [the moral laws and the final purpose] the first are useful for ascribing to the Author of Nature, the second for ascribing to man, those properties which contain the necessary condition of the possibility of both [God and the soul]; so that from this Idea a conclusion can be drawn as to the existence and constitution of these beings which are otherwise quite hidden from us.

Thus the ground of the failure of the attempt to prove God and immortality by the merely theoretical path lies in this, that