Masturbation Causes Insanity, Blindness, and Physical Degeneration

From roughly 1770 onward, the specter of masturbatory insanity haunted Britannica's medical entries and medical textbooks alike. The panic originated with a polemical tract, *Onania* (1716), which claimed masturbation caused catastrophic health consequences. Britannica dutifully recorded these claims as medical fact, and the belief became so widespread that patients diagnosed as insane were often assumed to be habitual masturbators. The mechanism, exhaustion of vital fluids or nervous degeneration, fit neatly within the prevailing physiology. As late as the 1880s–1890s, prominent alienists (as psychiatrists were called) still invoked masturbatory excess as a cause of mental illness. However, careful epidemiological observation revealed no correlation between masturbatory practice and insanity, and modern sexology (Kinsey, Masters & Johnson) demonstrated that masturbation is a normal aspect of human sexuality. Britannica's later editions gradually dropped references to masturbatory insanity, though the damage to generations of adolescents subjected to remedies and moral warnings had already been done. The episode represents one of medicine's most consequential moral panics, a reminder that medicalized shame can persist long after the underlying clinical claims are discredited.