"Of all the couples in the history of modern thought (Freud and Lacan, Marx and Lenin...), Kant and Sade is perhaps the most problematic: the statement "Kant is Sade" is the "infinite judgement" of modern ethics, positing the sign of equation between the two radical opposites, i.e. asserting that the sublime disinterested ethical attitude is somehow identical to, or overlaps with, the unrestrained indulgence in pleasurable violence."
Kant and Sade, the ideal couple. By Slavoj Zizek.