During the 60s, at a time when many leading philosophers were showing an interest in Sade, the French psychoanalyst Jacques Lacan also wrote an essay on the literary works of the libertine aristocrat D.A.F. de Sade, often called “The Divine Marquis”. That essay, entitled “Kant avec Sade”, is regularly cited but rarely discussed in any depth by philosophers and psychoanalysts, partly as a result of Lacan’s baroque style of writing, his sloppy formulations, and his suggestive language. However, in spite of this, Lacan’s text is worthwhile reading. The central idea is that Sade’s oeuvre reveals the truth of Kant’s moral philosophy. In his article, the author shows that this remarkable thesis can be understood in at least two ways. Moreover, it is also argued that Lacan’s thesis can be read in a reverse direction, although Lacan himself never says that explicitly. It will be shown in the third section that according to Lacan, Kant is the truth of Sade.