Abstract: The irreducible goal of Sade's writing does not concern erotism but the Idea, not desire but truth, not history but practice. This paper focuses on the passage from the empirical description to the transcendental idea, from pornography to pornology, or from fiction to truth. The central problem is: what, through his writing, is the enterprise of thought that Sade attempts to build? In Sade, the practical reason of evil is characterized by the experience of limit and the dialectical transformation. The stake of his writing does not, however, pertain to debauchery, crimes, profanation and so forth, as the most essential for Sade is the idea of evil — the idea from which all difficulties are derived, and through which the extraordinary movements of Sade's philosophy emerge. Sade's tales reveal the singular existence of the pervert, but each resonates "one and the only sense" of being by representing its own difference. This as such suggests the univocity of evil in Sade.

Key words: Marquis de Sade, limit, evil, univocity, transgression, French contemporary philosophy