On the evening of October 29, 1945, Jean-Paul Sartre delivered a much-
anticipated lecture, advertised as “Existentialism is a Humanism,” to an
overflow crowd in the Salle des Centraux on the Parisian Right Bank. As
he was already well known for his novels Nausea and the recently
published The Age of Reason and The Reprieve, his plays, The Flies and
No Exit, and his philosophical essays, especially the daunting master-
piece Being and Nothingness, his talk was seen as the manifesto for this
rapidly spreading style of thought. It is still the philosophical essay
that people read when they seek an introduction to his work and to this
movement in general. Yet it is the only piece that he openly regretted
having published.