Richard Freiherr von Krafft-Ebing (1840-1902) was a German-Austrian psychiatrist and early sexologist, whose book Psychopathia Sexualis: eine Klinisch-Forensische Studie, first published in 1886 (and translated into English in 1892), became a great influence within the emerging study of sexology. The book, which Krafft-Ebing continued to expand throughout twelve editions until his death, is a scientific study of sexual deviation consisting of over 200 case studies. Intended for the use of physicians, psychiatrists and judges (and written partly in Latin in order to discourage the general public from reading it), the book explores fetishism, sadism, masochism and homosexuality, as well as nymphomania, necrophilia, and incest. For Krafft-Ebing, any desire for sex unrelated to procreation was a deviation from the heterosexual norm, making, for example, gay sex a "perversion" of the sexual instinct.

The photographs featured here are part of Krafft-Ebing’s personal collection. It is unknown where they came from or who the people featured in the photographs are, although, at least the first two photographs appear to be unusual specimens of the "French postcard" which was so popular in the late-19th century. One assumes the photographs are linked to Krafft-Ebing’s studies, but as for how or where they were produced and procured is a mystery.