The upshot of all this discussion is that from the study of man’s body as an ethical machine, it appears that he who would formulate a list of the chiefly desirable traits or virtues should first carefully consider the total needs of the organism. This new catalogue of virtues will be based upon the realization that man possesses both a flexor and an extensor mechanism. We know already that many ailments of the body are traceable to a lop-sided use of it, by which is usually meant the acquisition of chronic fatigue-postures in the flexor muscles. Indeed, chronic postures are recognized to be of such paramount importance, that experts have been employed to devise adequate stretching exercises (actuating the disused extensor system) in order to restore the organic balance of a nation. Moreover, just as the hygiene of the body depends upon a liberal use of all of its muscles, so likewise the ethical balance of the organism can be maintained only by the cultivation and commendation of a sufficient variety of traits to provide an outlet for all the action-tendencies which man naturally possesses. Virtue, then, we may henceforth regard as being based directly upon our physiological needs, and not upon the assumption, so frequently employed in the past, that ideals must be unattainable in order to be respectable. Moreover, a strictly natural science of ethics will have a regard for the fact of individual differences among men, and, recognizing that blood-pressure, metabolism, talents, and capacities differ so widely as to make it impossible for any one trait to be the “highest” virtue for all persons, it will place the emphasis solely upon the needs of the individual case. Already this development has become wide-spread. The juvenile courts, the Society for Mental Hygiene, the National Child Welfare Association are all examples of an ethical technique based entirely upon the sciences of physiology, psychology, and medicine. This emancipation of ethics from official religion is one of the most momentous events in the history of civilization.