The _Critique of Judgment_ is at once the most interesting and the most difficult of Kant’s three _Critiques_. It seems to cover a much wider ground than either of the two earlier _Critiques_. It concerns itself with the relation of empirical investigation to the a priori principles of understanding discussed in the first _Critique_, with an attempt to bridge the gulf between the world of freedom and the world of nature as described in the second _Critique_, with a discussion of the principles of æsthetics and of the conflict between the rival claims of the principles of mechanism and teleology, a conflict which, since the discoveries of Darwin and the increasing interest taken in biology, is becoming every day more important. On all these points Kant has much of importance to say. Modern theories of æsthetic are mainly based on an acceptance of the distinctions which he first laid down clearly. Much modern philosophy of a type which is little in sympathy with the doctrines of the first _Critique_--Pragmatism, for example--is an elaboration of his account of the regulative principles which guide empirical investigation, while speculation on the rival methods of biology has hardly advanced beyond the solution suggested by Kant. Yet the very suggestiveness of this book makes it hard to understand. It is difficult to see the connection which Kant supposed to exist between these very various problems. The form of the book, like the form of the first _Critique_, is marked by subdivisions suggested by formal logic, which seem to have little or no connection with the subjects discussed under them, so that the whole is a curious combination of formal system and discursive content. Kant himself regarded this _Critique_ as the triumphant vindication of his whole system, in that it brought together and reconciled subjects which he had previously distinguished too sharply. Many later writers have thought rather that in it the inconsistencies which they believe to exist in Kant’s thought come to a head. We have not space here to vindicate the _Critique of Judgment_ as "the crowning phase of the critical philosophy," as a recent writer has called it, or to examine singly Kant’s treatment of the various subjects of interest with which it is concerned. It is important, however, to follow the connection which Kant supposed to exist between these different subjects. If we can understand that, we shall gain considerable insight into Kant’s system as a whole.