In Hemingway's short story of endurance and ethical conduct in the face of the meaninglessness of life, there are three symbols, the light, the use of repetition, and the nada.
A widower, the lonely old man, who has before attempted suicide, lingers in the cafe because he wants to drink where there is light. While the young waiter is irritated with the old man, wishing he would leave, the older waiter understands that the man's endurance of the meaningless of life can better be made in the light. He compliments the old man saying,
"He drinks without spilling Even now, drunk. Look at him."
The old man has discipline, but his despair is so great that darkness exacerbates his condition. In the light there is some hope, some order to things to which the man's desperate spirit can cling as life then is predictable. But, in the darkness he feels only the nothingness of his life.
The Spanish word for nothing, nada represents the absurbity and meaninglessness of life. This existential concept defines the emptiness, or void, that many have felt in their souls after returning from the world wars. Nothing really matters in life; all that one can do is create his own existence and give some meaning to his life by maintaining a stoic order. Otherwise, the nada will conquer the man.
When the older waiter goes to bed, he hopes that the daylight will give some meaning to his life and he can go to sleep because he feels, too, that all is a nothing and man, too, is nothing.
Hemingway's use of repetitive phrasing, such as beginning so many sentences with "The old man..." and phrases with nada and their imitation of the Lord's Prayer all suggest aesthetic appreciation along with the need for order if one is to survive the absurdity of life.