In one of the most famous set pieces of Jean-Paul Sartre’s Being and Nothingness (1943), he describes running into a café. He looks through the smoky atmosphere to the patrons. He hears “sounds of voices, rattling saucers, and the footsteps that fill it.” But despite this “fullness of being,” the scene is structured by an absence. For Sartre has come looking for a friend, who, he argues, is palpably not there. Sartre’s description draws attention to the two elements of his philosophy announced in the book’s title. An embodied and situated “being,” the human individual nonetheless participates in “nothingness” such that it is never fully controlled by physical or moral laws. How we act determines who we are, not vice versa. Or, in the laconic style of his 1945 slogan: “Existence precedes essence.”