Synopsis The Philosophical Library presents the most important thinkers through the ages and their most influential writings. Considered the father of psychoanalysis, Sigmund Freud revolutionized the study of human psychology with the concept of the unconscious, its role in individual behavior, and its significance in the dream state. He is perhaps best known for the idea that repressed sexual feelings can be a cause of neurosis. In this A to Z reference, key concepts and terms developed by Freud are clearly defined and explained in his own words. Readers will not only see what Feud really meant when he discussed dram interpretation, ago, the Oedipus complex, and the unconscious, but also hear him explain the treatment therapies he devised for abnormal behavior.