manifestation of the essential constitution of man as a knowing being. For those who accept the Kantian philosophy, it is accordingly the _magna charta_ of scientific work: the adequate formulation of the constitution which directs and justifies their scientific inquiries. It is a truism to say that among the Germans as nowhere else has developed a positive reverence for science. In what other land does one find in the organic law mention of Science, and read in its constitution an express provision that "Science and its teaching are free"? But this expresses only half of Kant's work. Reason is itself supersensible. Giving law to the material of sense and so constituting nature, it is in itself above sense and nature, as a sovereign is above his subjects. The supersensible world is thus a more congenial field for its legislative activity than the physical world of space and time. But is any such field open to human experience? Has not Kant himself closed and locked the gates in his assertion that the entire operation of man's knowing powers is confined to the realm of sense in which causal necessity dominates? Yes, as far as knowledge is concerned. No, as far as moral obligation is concerned. The fact of duty, the existence of a categorical command to act thus and so, no matter what the pressure of physical surroundings or the incitation of animal inclinations, is as much a fact as the existence of knowledge of the physical world. Such a command cannot proceed from nature. What is cannot introduce man to what ought to be, and thus impose its own opposite upon him. Nature only enmeshes men in its relentless machine-like movement. The very existence of a command in man to act for the sake of what ought to be--no matter what actually is--is thus of itself final proof of the operation of supersensible reason within human experience: not, indeed, within theoretical or cognitive experience, but within moral experience.