The famous, but still unknown to the domestic reader, the book of the 17th century English thinker is first published in Russian translation. What is melancholy? How does it relate to mental disorders - dementia and madness, rabies and lycanthrope? How do melancholy give rise to witchcraft and magic, stars and omens, food and sleep, pleasure and sadness, passions and excitement, poverty and wealth, self-love and vanity, love of knowledge and excessive study of science? The author considers the essence and causes of melancholy, in modern terms, as a philosopher and sociologist, psychologist and psychiatrist, with the involvement of a huge number of literary sources - from Antiquity to the New Age.