Monomania

Monomania was a nineteenth century psychiatric diagnosis describing a form of partial insanity conceived as a single psychological obsession occurring in an otherwise mentally sound individual, its name drawn from Greek roots meaning one and madness. French psychiatrist Jean-Etienne Dominique Esquirol coined the concept around 1810, proposing that mental disease could affect only a specific part of the mind rather than all mental faculties at once, and he and his colleagues divided monomanias into emotional, intellectual and volitional types according to their understanding of mental faculties. The diagnosis encompassed a range of specific manifestations, including bibliomania, an obsession with hoarding books, erotomania, a delusional romantic obsession, kleptomania, compulsive stealing, pyromania, an impulse toward fire-setting, and homicidal monomania, a sudden murderous impulse arising in an otherwise rational person. Although still recognized as one of seven official mental illness categories in the 1880 United States census, the diagnosis lost standing from the 1850s onward after sustained criticism and was eventually abandoned by psychiatric practice, though it retained influence in forensic contexts for some time.