Good stamp. 

Denis Diderot (5 October 1713 – 31 July 1784) was a French philosopher, art critic, and writer, best known for serving as co-founder, chief editor, and contributor to the Encyclopédie along with Jean le Rond d'Alembert. He was a prominent figure during the Age of Enlightenment. Diderot initially studied philosophy at a Jesuit college, then considered working in the church clergy before briefly studying law. When he decided to become a writer in 1734, his father disowned him. He lived a bohemian existence for the next decade. In the 1740s he wrote many of his best-known works in both fiction and non-fiction, including the 1748 novel Les Bijoux indiscrets (The Indiscreet Jewels). His fortunes improved significantly in 1766, when Russian Empress Catherine the Great, who heard of his financial troubles, generously bought his 3,000-volume personal library, amassed during his work on the Encyclopédie, for 15,000 livres, and offered him in addition a thousand more livres per year to serve as its custodian while he lived. He received 50 years' "salary" up front from her, and stayed five months at her court in Saint Petersburg in 1773 and 1774, sharing discussions and writing essays on various topics for her several times a week. Diderot's literary reputation during his life rested primarily on his plays and his contributions to the Encyclopédie; many of his most important works, including Jacques the Fatalist, Rameau's Nephew, Paradox of the Actor, and D'Alembert's Dream, were published only after his death.