its dependence upon oxygen, its optimal temperature, its rate of dying with different vital organs removed, and the like,—and so when a vitalist speaks of “_the_ Secret of Life,” he simply shows that he is still a worshipper of magic. Although the way of intellectual progress lies in another direction, yet, since the majority of mankind court mystery as a way of escape from the “despotism of fact,” the vitalist can be expected to lead a voluble resistance against a mechanistic ethics. Nevertheless, even he can perhaps be induced to recognize that although Psyche does seem to regulate Homo, yet it is always the structure of Homo that determines what manner of function he shall manifest. And if the mechanist can elicit this admission from the vitalist, he can at least maintain his chief contention. Otherwise, seeing that the mechanists are on the whole younger men than the vitalists, nature’s own slow processes will have to soften the asperities of this conflict. Having thus begun our outline of a mechanistic ethics by stating the chief points of its disagreement with certain traditional ways of thinking, let us now proceed to establish without interruptions the foundations upon which this science of human conduct is to be built. And first a word as to its antecedents. All modern scientific thinking, which is essentially a pertinacity of attention,—a dogged following upon a clue sagaciously intuited,—is our heritage from ancient Greek thought, and particularly from Socrates. And it is quite a significant, though oft-forgotten fact, that while almost all our scientific inquiry has been directed toward the conquest of physical nature, Socrates himself scorned to devote his powers to any but the subjects of ethics and the theory of knowledge. It is, then, something like a return to the chief interest of Greek life to employ the methods of general science in the analysis of the ethical problem. “Know _thyself_” was the well-known motto of Socrates; but it has required an infinitude of other knowledge before we could see clearly enough to know ourselves. Nevertheless, we may now say that in thus employing modern science strictly in the interest of ethics, the homage to Socrates is no less profound than the implied confidence in the trend of that civilization which originated in his brilliant mind.