General opinion has it that the boy instinctively plays Indians and follows the so-called tribal occupations as the direct result of his inheritance from some thousands of generations of savage ancestors who, willy nilly, have been doing these things all their lives. We commonly believe that the normal boy is possessed to throw stones at every moving object because his forebears got their livings or preserved their lives by throwing all sorts of missiles at prey and enemies, so that the fascination of sticks and clubs is but the reverberation of the not so very far off days when sticks and clubs were man’s only weapons. According to this doctrine, such a game as baseball is an epitome of man’s prehistoric activities. To throw accurately and to run swiftly, to hit a quick-moving object with a club, is to revive, symbolically, the most absorbing of ancestral activities and the most vivid of ancestral memories. As the girl, tending her doll, is recapitulating the experiences of a hundred thousand mothers before her, so the boy, in the varied activities of his gang, is reproducing the life of long departed clans and tribes. The instinctive interests of both boys and girls are the result of the experiences of their ancestors. All this, one need not point out, is the familiar recapitulation theory, the doctrine, that is to say, that the young of each species, our own included, tends to reproduce in the course of its youth the successive stages in the history of its ancestors. We are by turns invertebrates, gill-breathing vertebrates, lung-breathing vertebrates (we make the great change at birth), little monkeys, little savages, and finally civilized men and women. It is an illuminating theory, and one, moreover, which goes far toward explaining many aspects of our human nature which without it would be largely meaningless. Especially is it the key to the behavior of boys at the gang age. The normal boy between ten and sixteen is really living through the historic period which, for the races of northern Europe, began somewhere this side of the glacial period, and came to an end with, let us say, the early middle ages. He is, therefore, essentially a savage, with the interests of a savage, the body of a savage, and to no small extent, the soul of one. He thinks and feels like a savage; he has the savage virtues and the savage vices; and the gang is his tribe.