On the surface, the work of the Marquis de Sade appears to be a systematic transgression of every interdiction weighing upon civilized man. The anthropologist Claude Lévi–Strauss posits the incest taboo as the fundamental interdiction, the primal taboo which founds society. Not surprisingly, incest is prevalent in Sade's novels. In The New Justine, Verneuil, whose entire household is allied through multiple incests, argues in defense of his pet crime: “Let a father, a brother, idolizing his daughter or his sister, descend to the bottom of his soul and interrogate himself scrupulously about what he feels: he will see if that pious tenderness is anything other than the desire to fuck.” As represented by Verneuil, incest is the passion underlying the relation between brother and sister or father and daughter. Likewise for Lévi-Strauss, it is intercourse with the sister or the daughter that must be abandoned so the brother or father can partake in the generalized exchange of women constitutive of society.

Whereas for Sadean libertine and structuralist anthropologist, incest means father–daughter or brother–sister sex, for Freud the central configuration of incest – figured by the oedipal myth – is between son and mother. In the vast tableau of forbidden passions making up Sade's opus, mother–son incest is sorely underrepresented. And in all but one case of its occurrence it is consummated through anal intercourse, thus avoiding contact with the locus constitutive of the mother as mother.