But the echoes of the older naïve view of Man and his Nature sounded long after the rational scientific conception had become dominant. It is not so very long ago that psychology was little more than human psychology; nor has sociology long since gone outside the purely human for explanations of the facts of human society. Nowadays, however, psychology has a firm comparative basis and sociology finds much that is illuminating and helpful in the purely biological aspects of the human animal. Very naturally, then, we have had social science studying man as Man, with a capital M: biological science studying man as a natural animal. But now that modern trend of scientific synthesis which has brought forth a Physical-Chemistry and a Chemical-Physiology and a Bio-Chemistry, is combining the purely social and the purely biological studies of man into a new Bio-Sociology. And as one phase of this new partnership we have the subject of Eugenics--the science of racial integrity and progress, built upon the overlapping fields of Biology and Sociology. We can trace the idea, perhaps better the hope, of Eugenics from the modern times of ancient Greece. Plato laid stress upon the idea of the "purification of the State." In his Republic he pointed out that the quality of the herd or flock could be maintained only by breeding from the best, consciously selected for that purpose by the shepherd, and by the destruction of the weaklings; and that when one was concerned with the quality of his hunting dogs or horses or pet birds, he was careful to utilize this knowledge. He drew attention to the necessity in the State for a functionary corresponding to the shepherd to weed out the undesirables and to prevent them from multiplying their kind. Plato stated clearly the essential idea of the inheritance of individual qualities and the danger to the State of a large and increasing body of degenerates and defectives. He called upon the legislators to purify the State. But the legislators paid no heed. The able-bodied and able-minded continued to be sacrificed to the God of War; the degenerates and defectives--not fit to fight--were the ones left at home to become parents of the next generation. And to-day Greece remains an awful warning.