Sigmund Freud was a neurologist who worked as a doctor in Vienna’s General Hospital. In 1885, Wilhelm Fleiss, Freud’s friend and one of the most influential otolaryngologists of his time, suggested that he should study the sexual origins of “hysteria.” This is how Freud began studying psychology.

He used himself as a subject in his studies. He also used the help of his friend, Josef Breuer, who helped him develop psychoanalysis—Freud’s method for treating patients suffering from hysteria.

Freud believed that mental illness was caused by repressed emotions and memories which were still active in the mind but unnoticed by consciousness. He proposed bringing these memories into consciousness. To do that, people lie on a couch and discuss the events in their lives while Freud observes them from behind a desk. He would write down his observations about what he had heard and interpret them later.

Freud’s most famous discoveries were made while experimenting with “Anna O.,” a patient of Breuer’s. Anna O. was a young woman diagnosed with hysteria and had paralysis of her limbs, loss of vision, speech problems, and memory loss.

Breuer found out that during the periods when she didn’t have these symptoms, she would often recall some event or period during which they occurred and recover some function again. Breuer and Freud called these periods “hysterical relapses” and started experimenting with hypnosis as a method for bringing those memories to consciousness. These experiments were not successful, but from them, Freud came up with psychoanalysis.

In this new method, people lie on a couch and discuss the events in their lives while Freud observes them from behind a desk. He would write down his observations about what he had heard and interpret them later.

In 1938, Freud fled Austria to escape persecution by the Nazi administration, which came into power in Germany because of Hitler’s racial policies. In 1939, after arriving in England, he became a British citizen. After World War II, he continued writing and died at 83.

Freud also made some other discoveries that are not usually taught in schools. For example, he believed that dreams are the “royal road to the unconscious,” which can be used to understand an individual’s personality and motivations. He also thought there’s no such thing as an Oedipus Complex (in which boys feel sexual desire towards their mother) or Electra Complex (in which girls feel the same way about their father) and that children are not affected by incest.

Freud made several more discoveries that are not common knowledge, but the three above are the most important.