The second volume in the longitudinal study of gifted children in the United States of America supervised by Lewis Terman. An extensive discussion and analysis of IQ ratings is applied to the study of biographical data retained from historical figures known for their precocious talents in their time. Catherine Cox, with the aid of assistants, estimated and correlated the raw ability of 300 geniuses, and categorized them by the grade of their ability as judged by a summary of their personality. (Summary by Leon Harvey)