The History of Sexuality, Volume 1 begins with an account of the Repressive Hypothesis, Foucault's term for the widespread idea that modern society continues to struggle with the legacy of 19th-century sexual repression. The Repressive Hypothesis holds that we struggle to liberate ourselves from the imposition of silence and tight sexual morals that we have inherited from our Victorian forebears. Focuault's book follows from his attempt to answer a simple question: why do we believe this? Why do we feel as though we must liberate ourselves from sexual repression?
In what follows, Foucault undertakes a history of modern sexuality. A master of the counterintuitive observation, he begins his historical study by arguing that the opposite of the Repressive Hypothesis is true: instead of living under the imposition of silence, modernity has seen an utter explosion of new ways of thinking and talking about sex, stretching back as far as the late 17th century. But Foucault notes that these new forms of discourse about sex have also been tied inextricably to the changing history of power relations that mark our capitalist modernity.
By examining the apparently disparate histories of such disciplines as psychiatry, Catholic ritual, and population science (among others), Foucault argues that we have become not only a society obsessed with discovering the truth about sex, but a society that has come to see sex as the ultimate truth to be discovered. He argues that sexuality is a social construct, the product of many institutions of knowledge-production that have come to understand human subjects in particular and historically-specific ways. We have become a society that treats sexuality as that which reveals the ultimate secret of who we are, of our motives, of the source of our mental and emotional status. For Foucault, the political history of modern institutions of knowledge-production about sexuality is the history of how we came to see ourselves this way.