In principle, the discovery is as simple as its application is far-reaching. Both science and moral obligation exist. Analysis shows that each is based upon laws supplied by one and the same reason (of which, as he is fond of saying, reason is the legislator); but laws of such a nature that their respective jurisdictions can never compete. The material for the legislation of reason in the natural world is sense. In this sensible world of space and time, causal necessity reigns: such is the decree of reason itself. Every attempt to find freedom, to locate ideals, to draw support for man's moral aspirations in nature, is predoomed to failure. The effort of reason to do these things is contrary to the very nature of reason itself: it is self-contradictory, suicidal. When one considers the extent in which religion has been bound up with belief in miracles, or departures from the order of nature; when one notes how support for morals has been sought in natural law; how morals have been tied up with man's natural tendencies to seek happiness and with consequences in the way of reward of virtue and punishment of vice; how history has been explained as a play of moral forces--in short, the extent to which both the grounds and the sanctions for morality have been sought within the time and space world, one realizes the scope of the revolution wrought by Kant, provided his philosophy be true. Add to this the fact that men in the past have not taken seriously the idea that every existence in space, every event in time, is connected by bonds of causal necessity with other existences and events, and consequently have had no motive for the systematic pursuit of science. How is the late appearance of science in human history to be accounted for? How are we to understand the comparatively slight influence which science still has upon the conduct of life? Men, when they have not consciously looked upon nature as a scene of caprice, have failed to bring home to themselves that nature is a scene of the legislative activity of reason in the material of sense. This fact the Kantian philosophy brings home to man once for all; it brings it home not as a pious wish, nor as a precarious hope confirmed empirically here and there by victories won by a Galileo or a Newton, but as an indubitable fact necessary to the existence of any cognitive experience at all. The reign of law in nature is the work of the same reason which proceeds empirically and haltingly to the discovery of law here and there. Thus the acceptance of the Kantian philosophy not only frees man at a single stroke from superstition, sentimentalism and moral and theological romanticism, but gives at the same stroke authorization and stimulation to the detailed efforts of man to wrest from nature her secrets of causal law. What sparse groups of men of natural science had been doing for the three preceding centuries, Kant proclaimed to be the