In the first volume of The Role of Eroticism in Male Society, Hans Blüher lays the theoretical foundation for one of the most provocative sociologies of the early twentieth century. Rejecting explanations of the state and society based only on economics, spirit, utility, or convention, Blüher argues that human association must be traced back to Eros. Male society, in his account, is not a secondary social arrangement but a primal force rooted in male-male erotic life. The volume moves through sexuality, bisexuality, inversion, anxiety, repression, the unconscious, psychoanalysis, illness, healing, and the typus inversus. Drawing on Freud, Fließ, Weininger, Plato, and contemporary sexology, Blüher treats the typus inversus as both a psychological and sociological figure: the hidden bearer of men’s leagues, comradeship, male culture, and the deeper erotic structure behind state-forming humanity.