To trace out the former and; exhibit it by itself is his purpose in the Grundlegung der Metaphysik der Sitten, which he accordingly represents as a science purely a priori, exactly in the same way as he sets forth the Metaphysische Anfangsgr�nde der Naturwissenschaft.

He asserts in fact that the Moral Law, which without warrant, without deduction, or proof of any sort, he postulates as existing, is furthermore a Law knowable a priori and independent of all internal or external experience; it “rests” (he says) “solely on conceptions of pure Reason; and is to be taken as a synthetic proposition a priori” (Kritik der Praktischen Vernunft: p. 56 of fourth Edition; R., p. 142). But from this definition the implication immediately follows that such a Law can only be formal, like