Let us consider this waiter in the café. His movement is quick and forward, a little too precise, a little too rapid. He comes toward the patrons with a step a little too quick. He bends forward a little too eagerly; his voice, his eyes express an interest a little too solicitous for the order of the customer. Finally there he returns, trying to imitate in his walk the inflexible stiffness of some kind of automaton while carrying his tray with the recklessness of a tight-rope-walker by putting it in a perpetually unstable, perpetually broken equilibrium which he perpetually re-establishes by a light movement of the arm and hand. All his behavior seems to us a game. He applies himself to chaining his movements as if they were mechanisms, the one regulating the other; his gestures and even his voice seem to be mechanisms; he gives himself the quickness and pitiless rapidity of things. He is playing, he is amusing himself. But what is he playing? We need not watch long before we can explain it: he is playing at being a water in a café. There is nothing there to surprise us. The game is a kind of marking out and investigation. The child plays with his body in order to explore it, to take inventory of it; the waiter in the café plays with his condition in order to realize it. This obligation is not different from that which is imposed on all tradesmen. Their condition is wholly one of ceremony. The public demands of them taht they realize it as a ceremony; there is the dance of the grocer, of the tailor, of the auctioneer, by which they endeavor to persuade their clientele that they are nothing but a grocer, an auctioneer, a tailor. A grocer who dreams is offensive to the buyer, because such a grocer is not wholly a grocer. Society demands that he limit himself to his function as a grocer, just as the soldier at attention makes himself into a soldier-thing with a direct regard which does not see at all, which is no longer meant to see, since it is the rule and not the interest of the moment which determines the point he must fix his eyes on (the sight "fixed at ten paces"). There are indeed many precautions to imprison a man in what he is, as if we lived in perpetual fear that he might escape from it, that he might break away and suddenly elude his condition.
Jean-Paul Sartre, Being and Nothingness, pp. 101-2