The one of these prophets among biologists, President G. Stanley Hall, has lived to see his faith in the practical importance of the intensive study of childhood and adolescence justified by radical reforms in school and home. Hall should be revered by all lovers of youth as the apostle to adolescents. The other, Professor William McDougall, has done much to convince the thinking world that all of the social sciences and technologies must be grounded upon an adequate genetic psychology--a genetic psychology which shall take as full and intelligent account of behavior as of experience; of the life of the ant, monkey, ape as of that of man; of the savage as of civilized man; of the infant, child, adolescent as of the adult; of the moron, imbecile, idiot, insane, as of the normal individual; of social groups as of isolated selves. It is to McDougall we owe a most effective sketch--in his introduction to Social Psychology of the primary human emotions in their relations to instinctive modes of behavior. Hall, McDougall and such sociologists--lamentably few, I fear--as Graham Wallas would agree that for the attainment of peace we must depend upon some primary human instinct. I venture the prediction that no one of them would select fear as the safe basis. Instead, they surely would unite upon sympathy. Among animals preparedness for struggles is a conspicuous cause of strife. The monkey who stalks about among his fellows with muscles tense, tail erect, teeth bared, bespeaking expectancy of and longing for a fight, usually provokes it. We may not safely argue that lower animals prove the value of preparedness for war as a preventive measure! Among them, as among human groups, the only justification of militarism is protection and aggression. Preparedness for strife is provocative rather than preventive thereof. As individual differences, and resulting struggles, are due to ignorance, misunderstanding, lack of the basis for intelligent appreciation of ideals, motives and sympathy, so among nations knowledge of bodily and mental traits, of aims, aspirations, and national ideals fosters the feeling of kinship and favors the instinctive attitude of sympathetic cooperation.