The Marquis de Sade is famous for his forbidden novels, like Justine, Juliette and The 120 Days of Sodom. Yet, despite de Sade's immense influence on philosophy and literature, his work remains relatively unknown. His novels are too long, repetitive and violent. At last in The Philosophy of the Marquis de Sade, a distinguished philosopher provides a theoretical reading of de Sade. Airaksinen examines de Sade's claim that in order to be happy and free we must do evil things. He discusses the motivations of the typical Sadeian hero, who leads a life filled with perverted and extreme pleasures, such as stealing, murder, rape and blasphemy. Secondary sources on de Sade, such as Hobbes, Erasmus and Brillat-Savarin are analysed, and modern studies are evalated. The Philosophy of the Marquis de Sade greatly enhances our understanding of pain and perversion.