The interests of research have resulted in a division of labor between the fields of original and acquired nature in man. The examination of original tendencies has been quite properly connected with the study of inheritance. For the history of research in this field, the student is referred to treatises upon genetics and evolution and to the works of Lamarck, Darwin, DeVries, Weismann, and Mendel. Recent discoveries in regard to the mechanism of biological inheritance have led to the organization of a new applied science, "eugenics." The new science proposes a social program for the improvement of the racial traits based upon the investigations of breeding and physical inheritance. Research in eugenics has been fostered by the Galton Laboratory in England, and by the Eugenics Record Office at Cold Spring Harbor in the United States. Interest has centered in the study of the inheritance of feeble-mindedness. Studies of feeble-minded families and groups, as _The Kallikak Family_ by Goddard, _The Jukes_ by Dugdale, and _The Tribe of Ishmael_ by M'Culloch, have shown how mental defect enters as a factor into industrial inefficiency, poverty, prostitution, and crime. 4. The Investigation of Human Personality The trend of research in human nature has been toward the study of personality. Scientific inquiry into the problems of personality was stimulated by the observation of abnormal behavior such as hysteria, loss of memory, etc., where the cause was not organic and, therefore, presumably psychic. A school of French psychiatrists and psychologists represented by Charcot, Janet, and Ribot have made signal contributions to an understanding of the maladies of personality. Investigation in this field, invaluable for an understanding of the person, has been made in the study of dual and multiple personality. The work of Freud, Jung, Adler, and others in psychoanalysis has thrown light upon the rôle of mental conflict, repression, and the wishes in the growth of personality. In sociology, personality is studied, not only from the subjective standpoint of its organization, but even more in its objective aspects and with reference to the rôle of the person in the group. One of the earliest classifications of "kinds of conduct" has been ascribed by tradition to a disciple of Aristotle, Theophrastus, who styled himself "a student of human nature." _The Characters of Theophrastus_ is composed of sketches--humorous and acute, if superficial--of types such as "the flatterer," "the boor," "the coward," "the garrulous man." They are as true to modern life as to the age of Alexander. Chief among the modern imitators of Theophrastus is La Bruyère, who published in 1688 _Les caractères, ou les moeurs de ce siècle_, a series of essays on the manners of his time, illustrated by portraits of his contemporaries.