Richard von Krafft-Ebing’s (1840 – 1902) principal work is Psychopathia Sexualis: eine Klinisch-Forensische Studie (Sexual Psychopathy: A Clinical-Forensic Study), which was first published in 1886 and expanded in subsequent editions. The last edition from the hand of the author (the twelfth) contained a total of 238 case histories of human sexual behaviour.
This book popularized the terms sadism (derived from the brutal sexual practices depicted in the novels of Marquis de Sade) and masochism (derived from the name of Leopold von Sacher-Masoch). Krafft-Ebing also coined the term anilingus in this book.
Psychopathia Sexualis was one of the first books about sexual practices that studied homosexuality/bisexuality. It proposed consideration of the mental state of sex criminals in legal judgements of their crimes. During its time, it became the leading medico–legal textual authority on sexual pathology.