Heinrich Kaan (Russian: Генрих Каан; 8 February 1816 – 24 May 1893[1]) was a 19th-century physician known for his seminal contributions to early sexology.
Until then, concepts like deviation, aberration, and perversion were interpreted in a theological context as "false" religious beliefs or heresy.
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.
To Kaan, masturbation was at the root of all sexual disorders, deviations and unnatural lusts as it involved extravagant fantasies.
[11] Scholars have acknowledged Kaan's contributions, relative to those of Richard von Krafft-Ebing and Sigmund Freud.