Denis Diderot’s incarceration at Vincennes took place exactly halfway through his seventy years on earth. Prison became the dramatic pause that gave shape and meaning to both sides of his life. Before prison, Diderot had been a journeyman translator, the editor of an unpublished encyclopedia, and a relatively unknown author of clandestine works of heterodoxy; on the day that he walked out of Vincennes, he was forever branded as one of the most dangerous evangelists of freethinking and atheism in the country.
During Diderot’s three-month imprisonment, his jailer the Count d’Argenson and the count’s brother the marquis had looked on with amusement while this “insolent” philosophe had bowed and scraped before the authority of the state. In a diary entry from October 1749, the marquis related with glee how his brother the count had supposedly broken Diderot’s will. Solitary confinement and the prospect of a cold winter had succeeded where the police’s warnings had failed; in the end, the once-cheeky writer had not only begged for forgiveness, but his “weak mind,” “damaged imagination,” and “senseless brilliance” had been subdued. Diderot’s days as a writer of “entertaining but amoral books,” it seemed, were over.