Karl Jaspers (1883–1969) became famous primarily as a philosopher, one of the founders of existentialism, whose influence was noted by Albert Camus, Jean-Paul Sartre, and Hannah Arendt. However, Jaspers was not only a philosopher, but also a psychiatrist, and his doctoral dissertation, “General Psychopathology,” was the result of several years of work in a psychiatric hospital. Jaspers was deeply dissatisfied with the approaches to the study and treatment of mental illness that existed in his time; he believed that this branch of medicine was in deep crisis, and set himself the ambitious task of developing new scientific foundations for psychiatry. In fact, he created the philosophy of psychiatry, developed a new language and categorical apparatus for describing and classifying mental disorders. The first edition of General Psychopathology was published in 1913, when Jaspers was 30 years old; the book became his life's work, with each reprint he revised and expanded it - until 1959, when the 7th edition was published. This is a classic of psychiatric literature, a reference book for psychiatrists, which, even despite the intensive development of the sciences of the human brain and psyche in recent decades, remains indispensable. The diagnostic criteria accepted today, as well as the classification of mental disorders, continue to be based on the ideas and methods outlined in this work.