'The blood relation long remained an important element in the mechanisms of power, its manifestations, and its rituals. For a society in which the systems of alliance, the political form of the sovereign, the differentiation into orders and castes, and the value of descent lines were predominant; for a society in which famine, epidemics, and violence made death imminent, blood constituted one of the fundamental values. It owed its high value at the same time to its instrumental role (the ability to shed blood), to the way it functioned in the order of signs (to have a certain blood, to be of the same blood, to be prepared to risk one’s blood), and also to its precariousness (easily spilled, subject to drying up, too readily mixed, capable of being quickly corrupted). A society of blood-I was tempted to say, of “sanguinity” -where power spoke through blood: the honor of war, the fear of famine, the triumph of death, the sovereign with his sword, executioners, and tortures; blood was a reality with a symbolic function. We, on the other hand, are in a society of “sex,” or rather a society “with a sexuality”: the mechanisms of power are addressed to the body, to life, to what causes it to proliferate, to what reinforces the species, its stamina, its ability to dominate, or its capacity for being used. Through the themes of health, progeny, race, the future of the species, the vitality of the social body, power spoke of sexuality and to sexuality; the latter was not a mark or a symbol, it was an object and a target. Moreover, its importance was due less to its rarity or its precariousness than to its insistence, its insidious presence, the fact that it was everywhere an object of excitement and fear at the same time. Power delineated it, aroused it, and employed it as the proliferating meaning that had always to be taken control of again lest it escape; it was an effect with a meaning-value. I do not mean to say that a substitution of sex for blood was by itself responsible for all the transformations that marked the threshold of our modernity. It is not the soul of two civilizations or the organizing principle of two cultural forms that I am attempting to express; I am looking for the reasons for which sexuality, far from being repressed in the society of that period, on the contrary was constantly aroused. The new procedures of power that were devised during the classical age and employed in the nineteenth century were what caused our societies to go from a symbolics of blood to an analytics of sexuality. Clearly, nothing was more on the side of the law, death, transgression, the symbolic, and sovereignty than blood; just as sexuality was on the side of the norm, knowledge, life, meaning, the disciplines, and regulations.'
Michel Foucault, The History of Sexuality: Volume I: An Intrioduction, translator: Robert Hurley, publisher: Pantheon Books