If existence really does precede essence, there is no explaining things away by reference to a fixed and given human nature, In other words, there is… - Jean-Paul Sartre

If existence really does precede essence, there is no explaining things away by reference to a fixed and given human nature. In other words, there is no determinism, man is free, man is freedom. On the other hand, if God does not exist, we find no values or commands to turn to which legitimize our conduct. So, in the bright realm of values, we have no excuse behind us, nor justification before us. We are alone, with no excuses.

"But everything changes when you tell about life; it's a change no one notices: the proof is that people talk about true stories. As if there could possibly be true stories; things happen one way and we tell about them in the opposite sense. You seem to start at the beginning: "It was a fine autumn eveningin 1922." And in reality you have started at the end. It was there, invisible and present, it is the one which gives to words the pomp and value of a beginning... And the story goes on in reverse: instants have stopped piling themselves in a lighthearted way one on top of the other, they are snapped up by the end of the story which draws them and each one of them in turn, draws out the preceding instant: "It was night, the street was deserted." The phrase is cast out negligently, it seems superfluous; but we do not let ourselves be caught and we put it aside: this is a piece of information whose value we shall subsequently appreciate. And we feel that the hero has lived all the details of this night like annunciations, promises, or even that he lived only those that were promises, blind and deaf to all that did not herald adventure. We forget that the future was not yet there; the man was walking in a night without forethought, a night which offered him a choice of dull rich prizes, and he did not make his choice.
I wanted the moments of my life to follow and order themselves like those of a life remembered. You might as well try and catch time by the tail."

What do we mean by saying that existence precedes essence? We mean that man first of all exists, encounters himself, surges up in the world-and defines himself afterward.

I lean all my weight on the porcelain ledge, I draw my face closer until it touches the mirror. The eyes, nose, and mouth disappear. Nothing is left. Brown wrinkles show on each side of the feverish swelled lips, crevices, mole holes. A silky, white down covers the great slopes of the cheeks, two hairs protrude from the nostrils: it is a geological embossed map. And, in spite of everything, this lunar world is familiar to me. I cannot say I recognize the details. But the whole thing gives me an impression of something seen before which stupefies me: I slip quietly off to sleep.