"Studies in the Psychology of Sex, Volume 2" by Havelock Ellis is a book published in 1900. This groundbreaking work examines what nineteenth-century society called "sexual inversion"—homosexuality and gender variance—through case studies and scientific analysis. Ellis challenges prevailing views by arguing that same-sex attraction is often innate rather than a moral failing, and advocates for legal reform in England where such behavior remained criminalized. Initially suppressed in Britain, the book represents one of the first major English-language studies to treat its subjects with scientific objectivity and compassion.