A sentence that begins without its verb is already telling us something about the mood. "the lightbulb out" starts in lowercase and skips the "is" or "has gone," as if the poem had walked into the middle of a thought. Whatever happened, it has happened already, and the speaker is reporting it the way you might mutter it to yourself in a dark kitchen. The exclamation that follows, "That's tough!", is hard to place. It could be sympathy, sarcasm, or a pep talk aimed at no one but the speaker.
The voice that takes over is brisk and practical. "Tomorrow I'll buy a 100 Watt job / and screw it in." The word "job" turns the repair into something workmanlike, and "100 Watt" sounds like a label on a box. There is also a hint of overcompensation in it. The old bulb has failed, so the speaker will fight darkness with a stronger one. The plan is for tomorrow, though, which means the poem itself takes place in the dark, in the gap between the problem and the fix.
That gap is where the poem turns. "So what's darkness / among four walls." There is no question mark, so the line reads less like a question than a shrug, a way of cutting the problem down to size. "Four walls" does the cutting. The room becomes a box, and darkness inside a box seems small and manageable. The line break after "darkness" lets the word hang for a moment before the walls enclose it.
Then the poem leaves a blank line and drops in its strangest sentence: "The whole earth / in the closet next to the icebox." Like the opening, it has no verb, so the poem begins and ends in fragments, as if the sentences themselves were going dark. The line break after "earth" lets something enormous stand alone before it is stored away between a closet and a refrigerator. ("Icebox" is an old-fashioned word for a fridge, which gives the image a slightly worn, homely feel.) The whole planet is reduced to household clutter. The sound of the phrase "four walls" also seems to answer "whole earth," so that the cramped room and the entire world are set side by side.
What does that last image mean? The poem leaves it open, and a few readings are possible. In one, the speaker is genuinely comforted: if the earth is as ordinary as a closet, a burnt-out bulb is nothing. In another, the comfort is a cover. The speaker's world has shrunk to one dark room, and the cheerful errands and the "So what" are ways of not noticing. The title supports the second reading. "Nearing the Ceiling" suggests a limit, and the ceiling is also where the dead bulb sits. By the end, the poem has run up against the top of its small space, and everything, even the earth, has been packed in below it. That is an inference from the text, but the title gives the image a lot of weight.
The form helps this along. There is no rhyme and no regular meter, only short lines that follow the rhythm of speech, and the enjambments make the speaker sound as if he is thinking as he goes. Some sounds link the big and the small. The "w" in "Watt," "walls," and "whole" runs through the poem like a faint hum, and the plain, hard words "tough," "job," and "screw" keep the tone gruff. The layout matters too. Four lines come first, then a gap, then one line alone, like a closet set apart from the main room. The reader gets the same jolt of scale the speaker seems to feel.
The poem is worth reading because it holds comedy and unease in the same few lines without announcing either. It starts with the most trivial of household failures and ends with the planet in a cupboard, and it never raises its voice. How we talk ourselves out of small disasters says a lot about us, and so does how easily that talk can slip into something larger. The poem makes the reader decide whether the speaker is coping or simply alone in the dark.