Sigmund Freud was born in 1856 in Freiberg, Moravia, in a Jewish family which moved to Vienna a few years later. Here he found a very fertile ground for scientific research: the Austrian-German sphere had figures like Helmholtz, Fechner, Brücke, Mach and other outstanding scientists. In 1885 Freud went to Paris to attend the lectures of Charcot, who practised hypnosis as a therapy for hysteria; and he brought this practise back to Vienna. His first important work, "Studies in Hysteria" (1895), was produced in co-operation with J. Breuer, a psychiatrist who also helped him get established professionally. Some celebrated cases of hysteria are recorded in this work. The co-operation between Freud and Breuer ended because Breuer did not agree that the sexual component was the most important one in all neurotic phenomena, grouped into four classes. Then Freud established very close links with Wilhelm Fließ, a nose and throat specialist. Fließ had a curious idea about certain numerical ratios occurring in life events, such as the time between two successive births or between two nosebleeds, or the length of life itself. Freud was greatly fascinated by these counts, although they had no scientific basis. The sexual components of the most elementary actions in childhood, such as thumb-sucking or {\mengraflit pavor nocturnus, were proposed by Fließ and then organised by Freud in his theory, where the phases of psychosexual maturation are four: the oral, the anal, the phallic and the genital. In 1900 a very important work by Freud was published, "The Interpretation of Dreams"; it was updated in several subsequent editions. The main idea was that a dream is an effort to satisfy a desire originating in childhood. A dream is the night expression of the id. At the same time Freud began to think about some everyday errors, such as oversights, omissions and substitutions in names, explaining them as phenomena of repression. The most important theory is that of the psychic apparatus, where we meet the id, existing already at birth: it is controlled by the pleasure principle. Then the outer layers of the id give rise to the ego, controlled by the reality principle; the next development is up to the superego, which is the set of moral rules learned from the parents and acquired by the child at the age of 4-6 years. Another theory developed in various papers by Freud is his instinct theory. The life instinct (Eros) expresses itself through the libido, an aspect of the sexual drive, which is the inclination to preserve the individual or the species. The death instinct (Thanatos) reflects the tendency of everything structured to get back to an unstructured phase. Further works by Freud deal with the Oedipus complex, which is the inclination to kill one's own father; the guilty feeling finds release in religious rites. weiterlesen