Authors:

Man exists, turns up, appears on the scene and only afterwards, defines himself

Martin Heidegger, Simone de Beauvoir, Jean-Paul Sartre (2016). “The Philosophical Library Existentialism Collection: Essays in Metaphysics, The Ethics of Ambiguity, and The Philosophy of Existentialism”, p.164, Open Road Media
Man exists, turns up, appears on the scene and only afterwards, defines himself