Existentialism and Humanism (or "Existentialism is a Humanism", French: L'existentialisme est un humanisme) is a 1946 philosophical work by Jean-Paul Sartre. Widely considered one of the defining texts of the Existentialist movement, the book is based on a lecture called "Existentialism is a Humanism" that Sartre gave at Club Maintenant in Paris, on October 29, 1945.