Science and metaphysics or philosophy, though seeming often to be at war, with their respective adherents often throwing jibes and slurs at each other, are really the most intimate allies. The philosophic movement is simply the coming to consciousness of this claim of the individual to be able to discover and verify truth for himself, and thereby not only to direct his own conduct, but to become an influential and decisive factor in the organization of life itself. Modern philosophy is the formulation of this creed, both in general and in its more specific implications. We often forget that the technical problem “_how_ knowledge is possible,” also means “how _knowledge_ is possible”; how, that is, shall the individual be able to back himself up by truth which has no authority save that of its own intrinsic truthfulness. Science, on the other hand, is simply this general faith or creed asserting itself in detail; it is the practical faith at work engaged in subjugating the foreign territory of ignorance and falsehood step by step. If the ultimate outcome depends upon this detailed and concrete work, we must not forget that the earnestness and courage, as well as the intelligence and clearness with which the task has been undertaken, have depended largely upon the wider, even if vaguer, operation of philosophy. But the student of philosophy knows more than that the problem of knowledge has been with increasing urgency and definiteness the persistent and comprehensive problem. So conscious is he of the two opposed theories regarding the nature of science, that he often forgets the underlying bond of unity of which we have been speaking. These two opposing schools are those which we know as the sensationalist and the intellectualist, the empiricist and the rationalist. Admitting that the dominance of the question of the possibility and nature of knowledge is at bottom a fundamental question of practice and of social direction, is _this_ distinction anything more than the clash of scholastic opinions, a rivalry of ideas meaningless for conduct? I think it is. Having made so many sweeping assertions I must venture one more. Fanciful and forced as it may seem, I would say that the sensational and empirical schools represent in conscious and reflective form the continuation of the principle of the northern and barbarian side of medieval life; while the intellectualist and the rationalist stand for the conscious elaboration of the principle involved in the Græco-Roman tradition.