With the imperative Form of Ethics, which in Chapter II. we proved to be a _petitio principii_, is directly connected a favourite idea of Kant's, that may be excused, but cannot be adopted. Sometimes we see a physician, after having employed a certain remedy with conspicuous success, henceforth prescribing it for almost all diseases; to such a one Kant may be likened. By separating the _a priori_ from the _a posteriori_ in human knowledge he made the most brilliant and pregnant discovery that Metaphysics can boast of. What wonder then that thereafter he should try to apply this method, this sundering of the two forms, everywhere, and should consequently make Ethics also consist of two parts, a pure, _i.e._ an _a priori_ knowable part, and an empirical? The latter of these he rejects as unreliable for the purpose of founding Ethics. 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 Anfangsgründe 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 everything else known _a priori_, and consequently has only to do with the =Form= of actions, not with their =Essence=. Let it be thought what this means! He emphatically adds (p. vi of the preface to the _Grundlegung;_ R., p. 5) that it is "useless to look for it either subjectively in man's nature, or objectively in the accidents of the external world," and (preface of the same, page vii; R., p. 6) that "nothing whatever connected with it can be borrowed from knowledge relating to man, _i.e._, from anthropology." On page 59 (R., p. 52) he repeats, "That one ought on no account to fall into the mistake of trying to derive one's principle of morality from the special constitution of human nature"; and again, on page 60 (R., p. 52), he says that, "Everything derived from any natural disposition peculiar to man, or from certain feelings and propensities, or indeed from any special trend attaching solely to human nature, and not necessarily to be taken as the Will of =every rational being=," is incapable of affording a foundation for the moral law. This shows beyond all possibility of contradiction that Kant does not represent the alleged moral law as a _fact of consciousness_, capable of empirical proof--which is how the later would-be philosophers, both individually and collectively, wish to pass it off. In discarding every