The sequel and development of the first Criticism are found in Kant's works on ethics, aesthetics, teleology and religion. Only in one supplementary chapter, and in casual indications as need arises, has Kant made any pronouncement on his view of Philosophy as a whole and as a system. That it is and can only be a system, when it really engages on reconstruction in theory, was of course his fundamental insight. But in his stage of _Zetesis_[2], of testing and sifting the sound from the professed, he has confined himself to breaking up the mass piecemeal, and leaving each result in its turn to corroborate and correct the other. Sense and intellect may spring from a common stem; but let us, he says, deal with them in their apparent separateness. Reason practical must no doubt be identical at bottom with reason theoretical: all the more convincing will be the undesigned coincidence between the results of an inquiry into the principles of science, and one into the principles of morals. We have seen that science ultimately rests--though it does not discuss it and would indeed be incompetent to do so--on a faith, a hope, a postulate of the ultimate supremacy of intelligence,--the faith of reason in its own power (not verifiable indeed by an exhaustive list of actual results)--or in the rationality of the world. For science--though a kind of action and a part of conduct--is a sort of inactive action: an _enclave_ in the busy world, a period of preparation for the battle of life. In the field of conduct the ultimate presupposition, which was for the luxury of science called a reasonable faith or faith of reason, makes itself felt in the more forcible form of a categorical imperative.