A Viennese neurologist and psychologist (1856–1939). Freud's work may be divided into three areas: his invention of psychoanalysis as a therapeutic technique, his theory of personality (ego, ID and superego), and his social philosophy. While each of Freud's ideas is still hotly debated, few people would dispute his enormous and widespread influence in making the twentieth century more aware than any previous age of the power of the irrational and the unconscious in human affairs.