"Historians have argued [that] the men involved in [many of history’s] same-sex relationships should not retrospectively be classified as homosexual, since no concept of the homosexual existed in their culture and they did not organize their emotional lives as homosexuals; many of them were also on intimate terms with women and went on to marry. Nonetheless, the same historians persist in calling such men heterosexual, as if that concept did exist in the early nineteenth century [or other earlier time periods]. In doing so they mistake the fact that men who passionately and physically expressed their love for other men were considered normal for their having been considered heterosexual, as if it were not the very inconsistency of their emotional lives with contemporary models of heterosexuality that made them seem curious to historians in the first place. If homosexuality did not exist in the early nineteenth century, the neither did heterosexuality, for each category depends of its existence on the other. The very capacity of men to shift between male and female love objects demonstrates that a different sexual regime governed their emotions. ‘Normal’ men only became ‘heterosexual’ men in the late nineteenth century, when they began to make their ‘normalcy’ contingent on their renunciation of such intimacies with men."
— George Chauncey, Gay New York: Gender, Urban Culture, and the Making of the Gay Male World 1890-1940