Sigmund FreudSigmund Freud (1856-1939) was an Austrian psychiatrist and the founder of psychoanalysis. Considered the most influential psychological theorist of the twentieth century, Freud's theories have had an enormous influence on art, literature, and social hinking. Freud's fundamental idea was that all humans are endowed with an unconscious in which potent sexual and aggressive drives, and defenses against them, struggle for supremacy. His first major work was The Interpretation of Dreams, which established the importance of the psychoanalytical movement. His other writings include Three Essays on the Theory of Sexuality, Group Psychology and the Analysis of the Ego, The Future of an Illusion, The Ego and the Id, and Beyond the Pleasure Principle. Read More Read Less