Sigmund Freud

Sigmund Freud was born on 6 May 1856 in Freiberg, Moravia, to a Jewish wool merchant. The family moved to Vienna when he was three, and the city held him for nearly eight decades. He entered Vienna's medical school in 1873 and trained in Ernst Brücke's lab, beginning as a laboratory naturalist rather than a healer of the soul.

The pivot came in 1885 with a Paris fellowship under Jean-Martin Charcot, whose work on hysteria persuaded Freud that neuroses were functional, not organic. His collaboration with Josef Breuer produced Studies on Hysteria (1895), the founding document of the talking cure. He soon abandoned hypnosis for free association, and The Interpretation of Dreams (1900) declared dream work "the royal road to the unconscious".

His model of the mind evolved across decades. The early scheme of conscious, preconscious and unconscious gave way in 1923 to The Ego and the Id, in which id, ego and superego stand in tension. After the First World War and his daughter Sophie's death, Beyond the Pleasure Principle (1920) introduced the death drive. Transference, repression and defence mechanisms became the working vocabulary of psychotherapy.

The movement he led was riven by defections — Adler in 1911, Jung in 1914 — and by external critique. Karl Popper judged psychoanalysis a pseudo-science for lack of falsifiability; later historians showed his outcomes for Dora and the Wolf Man diverged from the records. His 1884-86 enthusiasm for cocaine helped addict his friend Ernst von Fleischl, and his framing of female sexuality and homosexuality falls below today's standards.

The last sixteen years brought jaw cancer and exile. From 1923 he endured thirty-three operations while writing Civilization and Its Discontents (1930). After Austria's annexation in 1938 he fled to London, dying there on 23 September 1939. Whatever the fate of his theories, Freud gave the mind a depth dimension — and a method for exploring it — that the twentieth century could not unthink.