A person sits in the middle of the day, doing something ordinary: going over their accounts. The poem is only a few lines long, yet it makes a surprising leap from that dull task to a thought about God, who "may be / little better than bread."
The phrase can be read in more than one way. It might sound a bit bleak, as if God is no more than a basic necessity, something to fill an empty stomach. But the title, "Sustenance," nudges us toward a warmer reading. Bread is what keeps us alive, so comparing God to it makes the divine seem humble, close at hand and essential. The word "may" keeps the speaker honest and unsure.
The mood is quiet, dry and thoughtful. Noon is bright and plain, with no mystery to hide in, and the speaker's wry tone suggests a mind weighing what really counts, perhaps finding a small comfort in the everyday.