7. Play interests were keen among these children, though the play was often of an unusual kind. "Solitary play" is repeatedly described. Of Emerson, his biographer says: "I don't think he ever engaged in boys' plays, not because of any physical disability, but simply because from earliest years he dwelt in a higher sphere." Others are said to have been "disinclined to general intercourse." Instead of joining in the usual childish games, Newton preferred to play with his machines, Darwin with his collections, Shelley to read, Stevenson to make clay engines, and Edison to mix his chemicals. Of Byron it was written: "The love of solitude and of meditation is already traceable in the child. He loves to wander at night among the dark and solitary cloisters of the abbey." To quote Yoder: "Solitude seems to have played a rather striking role in the lives of these great men. Either by nature or by opportunity, they have stayed a great deal alone." Nevertheless, many of the fifty persons studied by Yoder enjoyed physical activity. Washington loved outdoor sports, Schiller was a leader in athletics, Byron was an enthusiastic swimmer and rider, and Lincoln was the champion wrestler and woodcutter of his neighborhood. 8. The popular idea that great men owe their success to their mothers' influence upon their education does not receive verification from a study of these cases. The mother's place seems very often to have been filled by some other person, frequently an aunt, either because the mother had died, or because there were many other children to care for. "The role of the aunt stands out prominently." 9. These great persons were, in the decided majority of cases, derived from well-to-do families. Most of them were privately educated, by tutors or in private schools. Very few were "self made." TERMAN'S INFERENCES FROM BIOGRAPHY Terman (20) has effected an interesting advance over Yoder's method, in the interpretation of evidence from the biography of adults. [2] By analyzing data in the biography of Francis Galton, and by relating these data to modern knowledge of mental tests, Terman derives that the IQ of Francis Galton in childhood must have been not far from 200. As Terman has elsewhere pointed out, these attempts to study genius in childhood by inference from the biography of adults are very unsatisfactory. In the first place, only those whose potentialities have been realized are included in such study. Since factors other than innate intellectual power act also as determinants of eminence, we cannot be sure whether equal capacity for selective thinking may have existed in persons who died before the age of achievement, who were younger sons, who were girls, or who were the children of the poor. Moreover, such evidence as can be gleaned concerning those who have achieved eminence is comparatively unsystematic and unreliable as regards childhood.