Greek philosophy had an equally high opinion of human nature, of the human body, and of representations of the human body. Just as Greek art aimed at the presentation of the body of man, so Greek philosophy proclaimed the nobility of all human qualities, and inculcated the doctrine of a harmonious development of all sides of human nature.[4] Such a doctrine was formulated by Plato, and became a fundamental principle of the Old Academy; the New Academy assumed it, and handed it on to the Sceptics. According to Xenocrates (fourth century), who belonged to the Old Academy, happiness consisted not only in the possession of human virtue, but in the accomplishment of all natural acts.[5] The principle of a worship of human nature is in itself rather vague, and it is not surprising that disputes and contradictions arose in relation to its application. Thus Plato excluded pleasure from his conception of the good, while Aristotle, Plato’s pupil, held a contrary opinion. For the latter pleasure was the natural motive of human action, and its attainment was associated as intimately with the perfect life as beauty and health were associated with the perfect human body.[6] Under the name _Matriopathy_ there arose, in the ancient world, a doctrine the object of which was the study of the goal of natural morality. This doctrine was held by many philosophers, but these applied it to the details of actual life in very different fashions. Thus, for the Stoics, the _summum bonum_ and happiness, the most lofty aim, could not be found except by conforming life to nature. Conduct was to be brought into harmony with the rational order of nature in such a fashion that every conscious and rational being would perform no actions that could not be deduced from the general law.[7] The same principle of a life in harmony with nature led the Epicureans to the conclusion that “pleasure is a natural good, that is to say, a condition conformable with nature, and so bringing with it intrinsic contentment.”[8] Setting out from the same fundamental principle, the theories of the Stoics and Epicureans led in opposite directions. The Roman philosophers adopted the principle of a life strictly natural. Seneca, for instance,[9] enunciated the maxim: “Take nature as your guide, for so reason bids you and advises you; to live happily is to live naturally.” Without following through the centuries the development of the idea in detail, I may content myself with saying that resort has been made to it, wherever there was sought, outside the sanction of religion, a rational principle to guide human conduct. It recurs even among those convinced Christians who rebelled against the asceticism and hatred of human nature that became prevalent in the early centuries of the Christian era.