Like Albert Camus himself, Daru is a Frenchman born in Algiers. Thus, he is a man somewhat divided; so, when the French gendarme leaves the Arab with him, Daru is ambivalent about what to do; moreover, he is angered that he should be placed in the position he has,
That man's stupid crime revolted him, but to hand him over was contrary to honor; just thinking of it made him boil with humiliation.
And so, he decides to let the Arab decide his fate for himself, returning honor to the man. But as they sleep in the same room in the night, Daru feels a strange sense of brotherhood with the Arab. Nevertheless, the next day, Daru sets him free, with money and food, only to see the Arab standing still. Finally the Arab surrenders his fate to others as he "walks slowly on the road to prison."
Daru's heart is heavy. He is disappointed that the man has not chosen to return to his own people, for the Arab has surrendered to others the determination of his fate. And, yet, Daru realizes, he was never free because the others in his village would punish him, anyway. Like himself, the Arab is also tormented by the allusion of free choice.
Similarly, Daru feels tormented by the illusion of free choice. "In this vast landscape he had loved so much, he was alone." There is an indifference to man's plight in nature, and in his aloneness, man's existence is absurd and really without any clear order or meaning.