Dr. Sigismund Freud (later changed to Sigmund) was a neurologist and the founder of psychoanalysis, who created an entirely new approach to the understanding of the human personality. He is regarded as one of the most influential - and controversial - minds of the 20th century. In 1873, Freud began to study medicine at the University of Vienna. After graduating, he worked at the Vienna General Hospital. He collaborated with Josef Breuer in treating hysteria by the recall of painful experiences under hypnosis. In 1885, Freud went to Paris as a student of the neurologist Jean Charcot. On his return to Vienna the following year, Freud set up in private practice, specialising in nervous and brain disorders. The same year he married Martha Bernays, with whom he had six children. Freud developed the theory that humans have an unconscious in which sexual and aggressive impulses are in perpetual conflict for supremacy with the defences against them. In 1897, he began an intensive analysis of himself. In 1900, his major work 'The Interpretation of Dreams' was published in which Freud analysed dreams in terms of unconscious desires and experiences.