 The genealogical attempt to historicize the body is prominent also in The History of Sexuality, Vol. 1, but now Foucault’s target is the naturalist explanations of sex and sexuality. At the end of the book Foucault takes up the question of whether we can find a scientific truth about sex. He makes clear that his genealogical investigation of sexuality implies a challenge to a certain kind of explanatory framework of sexuality and gender: the idea of sex as a natural foundation or an unobserved cause, which supports the visible effects of gender and sexuality. He critically appraises the idea of a natural, scientifically defined true sex by revealing the historical development of this form of thought. He does not claim that sex, understood as the categories of maleness and femaleness, was invented in a particular historical period. He rather analyses the ways in which these categories were founded and explained in discourses claiming the status of scientific truth, and how this allegedly “pure” explanation in fact constituted these categories so that they were understood as “natural.” This idea has had enormous influence on feminist philosophers and queer theorists. Judith Butler has appropriated this idea in her influential book Gender Trouble to argue that allegedly scientific ideas of sex as a natural and necessary ground for sexual and gendered identities in fact have a normative function: they constitute our conceptions of “normal” men and women and their “natural” sexual desire for each other.