In Ernest Hemingway’s short story “A Clean Well-Lighted Place,” the older waiter, at the end of the story, contemplates a personal version of the Lord’s Prayer that emphasizes the idea of nothingness:

Our nada who art in nada, nada be thy name thy kingdom nada thy will be nada in nada as it is in nada. Give us this nada our daily nada and nada us our nada as we nada our nadas and nada us not into nada but deliver us from nada . . . .

This skewed version of the prayer is significant for a number of reasons, including the following:

• It suggests that not even God seems, to the old waiter, an alternative to nothingness.  Whereas God has traditionally been seen by Christians as the source of all being – of everything that is – here God himself is nothing. The quoted passage suggests that God indeed may not exist.
• The passage suggests that if God does not exist, heaven does not exist either. There may be no beautiful, eternal alternative to the suffering and alienation of the world as we know it.
• If God and heaven do not exist, then it makes little sense to pray to God or to hope for heaven.
• If God and heaven do not exist, there is no divine future to look forward to, contemplate, or take solace in.
• If God does not exist, then evil itself may not exist, and certainly there seems no divine answer or alternative to evil if evil does in fact exist.

In short, the old waiter’s contemplation suggests a thorough-going nihilism that eliminates one of the main alternatives – God – to the idea of nothingness. The tone of the old waiter’s thoughts suggests that he does not take the idea of God seriously and that he is almost willing to mock that idea. Certainly he seems to fear no divine retribution, apparently because he assumes that there is no such thing as the divine.

In Ernest Hemingway’s "A Clean Well-Lighted Place," why is the "nada" prayer central to understanding the theme of the story and the perspective of the older waiter?

The thematic concerns of Hemingway's 1933 story have to do with the divide between youth and age and whether life has any meaning beyond what we ascribe to it. 

The perspective of the older waiter is that the old man who comes to the cafe to drink deserves to be treated with compassion and dignity. He is sympathetic about the old man's suicide attempt and obvious loneliness and isolation.  The younger waiter is self-absorbed and cares nothing for the old man, seeing him only as a nuisance and an obstacle to getting home to his wife. The older waiter understands that the old man finds meaning in the simple pleasure of enjoying a few brandies in a "clean, well-lighted place," because he has concluded that life is essentially devoid of meaning beyond what we create for ourselves.  The younger waiter is deluded by his own youth; he has yet to figure out that life is meaningless.

The "nada prayer" expresses the older waiter's belief that life is meaningless except for what we choose to make meaningful. He finds purpose in providing a clean and orderly place for the old man and others like him (including himself) to spend time. To him, that is meaningful. The prayer expresses that life is meaningless and that the rituals of religion (praying) and the notion of an afterlife are also meaningless. The tangible phenomena of a drink, light, and a clean place are concrete and meaningful, though temporary.