He made sexology into a scientific discipline that drew on biology, medicine, psychology and culture. He was the first person to be very vocal about homosexuality not being a pathological condition. He wrote several interesting books, including the classical work, A History of Prostitution. His interest in anthropology led him to become an ardent proponent of eugenics. He wrote the biography of Marquis de Sade (he was the one that managed to dig out Sade’s lost book The 120 Days of Sodom). Not bad for someone who died at 50.