Hassner, Pierre “Immanuel Kant." Ed. Leo Strauss and Joseph Cropsey, The History of Political Philosophy. University of Chicago Press, 1987.
“Kant has given politics a place both central and derivative in his philosophy. In his 3 chief works (Critique of Pure Reason, 1781; Critique of Practical Reason, 1788; Critique of Judgment, 1790) he speaks of politics rarely and only by allusion except in one paragraph of the critique of judgment. Where he explicitly presents a political teaching, he does so through the medium either of a doctrine of law or of alas the feet of history. Is explicitly political writings are mostly brief and occasional. The concepts and practical proposals that they contain confirm the thought that they are essentially a means of relating to each other to already existing universes: that of the Kantian system as developed in the 3 critiques and that of modern natural rights as developed by Hobbes, Locke, and especially Rousseau. Kant sometimes transcends his masters; but even when he does so, as in his doctrine of perpetual peace through international organization, his originality lies not in the contents of the proposal (borrowed in this case from projects such as those of the Abbe De St. Pierre, on which Rousseau had commented) but in the novel philosophic basis and scope that he gives it, expressing it in legal terms that claim to be independent of all experience and founding it on his moral philosophy and his philosophy of history.”