Though Kant’s great work, the “Critick of pure Reason,” which created an epoch in the history of philosophy, did not appear till 1781; yet had he previously shown an approach towards the same standpoint in several smaller treatises, and particularly in his inaugural dissertation which appeared in 1770, “_Concerning the form and the principles of the Sense-World and that of the Understanding_.” Kant himself refers the inner genesis of his critical standpoint to Hume. “I freely confess,” he says, “that it was David Hume who first roused me from my dogmatic slumber, and gave a different direction to my investigations in the field of speculative philosophy.” The critical view therefore first became developed in Kant as he left the dogmatic metaphysical school, the Wolffian philosophy in which he had grown up, and went over to the study of a sceptical empiricism in Hume. “Hitherto,” says Kant at the close of his Critick of pure Reason, “men have been obliged to choose either a dogmatical direction, like Wolff, or a sceptical one, like Hume. The critical road alone is yet open. If the reader has had pleasure and patience in travelling along this in my company, let him now contribute his aid in making this by-path into a highway, in order that that which many centuries could not effect may now be attained before the expiration of the present, and the reason become perfectly content in respect of that which has hitherto, but in vain, engaged its curiosity.” Kant had the clearest consciousness respecting the relation of his criticism to the previous philosophy. He compares the revolution which he himself had brought about in philosophy with that wrought by Copernicus in astronomy, “Hitherto it has been assumed that all our knowledge must regulate itself according to the objects; but all attempts to make any thing out of them apriori, through notions whereby our knowledge might be enlarged, proved, under this supposition, abortive. Let us, then, try for once whether we do not succeed better with the problems of metaphysics, by assuming that the objects must regulate themselves according to our knowledge, a mode of viewing the subject which accords so much better with the desired possibility of a knowledge of them apriori, which must decide something concerning objects before they are given us. The circumstances are in this case precisely the same as with the first thoughts of Copernicus, who, finding that his attempt to explain the motions of the heavenly bodies did not succeed, when he assumed the whole starry host to revolve around the spectator, tried whether he should not succeed better, if he left the spectator himself to turn, and the stars on the contrary at rest.” In these words we have the principle of a subjective idealism, most clearly and decidedly expressed.