sentences:  The three-word formula originated in his 1945 lecture "Existentialism Is a Humanism", though antecedent notions can be found in Heidegger's "Being and Time".The Sartrean claim is best understood in contrast to the scholastic thesis that "essence" precedes "existence", i.e.a typical claim for this traditional thesis would be a human is essentially selfish, or that they are a rational being.