For most of the last century, the domains of personality and emotion were mainly the province of literature and philosophy. The social sciences and psychiatry began to address these phenomena in the latter half of the 20th century with mixed success. The categories that are widely used in the study of both personality and emotion are those that first emerged in the earliest eras of scholarship in these arenas. Traditional personality theory and the descriptive nosology of psychiatry were important influences on the development of these constructs.