Heinrich Kaan
Heinrich Kaan (; 8 February 1816 – 24 May 1893) was a 19th-century physician known for his seminal contributions to early sexology. Different sources identify him as Ruthenian (an ethnic group living in what is now Belarus and Ukraine) or as Russian. He was the personal physician to the Czar. Section::::"Psychopathia Sexualis". Kaan is primarily known for an early scientific approach to sexology i.e. a scientifically based theoretical study of sex as opposed to earlier fields of erotology—the more practical study of lovemaking. He published his main work "Psychopathia Sexualis" in 1844 in Leipzig in Latin and it  has been translated into English and German. A direct translation of the title is Psychopathies of Sexuality. In this work he reinterpreted the Christian sexual sins as diseases of the mind. Until then, concepts like "deviation", "aberration", and "perversion" were interpreted in a theological context as "false" religious beliefs or heresy. Kaan's novel idea was to turn them into medical concepts, to reinterpret them as mental diseases. Physicians and psychiatrists after him were quick to take up these ideas - a process which collectively is referred to as the "medicalization of sin" in cultural history. It is also referred to  as "degeneracy theory". Kaan's work was within the "onanism literature" tradition of his time. To Kaan, masturbation was at the root of all sexual disorders, deviations and unnatural lusts as it involved extravagant fantasies. He also considered heterosexual intercourse as psychopathological, if it comprised sexual fantasies. His main goal was to fight such sexual psychopathies, above all masturbation. Michel Foucault referred to Kaan's work in his mid-1970s lectures on the discourse of the nature of normality and abnormality. According to Foucault Kaan's work was the first medical text exclusively devoted to the study of sexuality. However, Foucault  recognized it as a symptom of a shift in the discourse on sexuality, rather than necessarily an influential work in itself. Scholars have acknowledged Kaan's contributions, relative to those of Richard von Krafft-Ebing and Sigmund Freud. Michel Foucault said during a course of lectures he did in 1974-75 at the Collège de France, that the "Psychopathia Sexualis” (1844)" “was the first treatise of psychiatry to speak only of sexual pathology but the last (monograph) to speak of sexuality solely in Latin”