Four words, no punctuation, no capital letter, and a title that is only a row of asterisks: Grenier gives the reader almost nothing to hold, then makes that almost-nothing feel strangely exact. The poem describes a bodily sensation, the moment when breathing goes so well that the lungs, normally invisible and ignored, announce themselves as something fitted together with care. Its central idea is that ease can be registered as craftsmanship, with physical well-being felt as a well-made joint.
Everything hangs on "mitred". A mitre joint is what a carpenter cuts at the corner of a picture frame: two pieces of wood, each sawn at an angle, meet in a clean seam with no overlap and no gap. Moving that image into the chest is odd and slightly comic, but it works. The word suggests edges that meet and stay closed, fullness without strain. It also sets hard, angular joinery against the soft, spongy organ it describes, so the sensation is of order laid over something yielding. The lungs feel tidy and contained, as if a breath had been measured before it was taken.
"Nicely" is the quiet partner to that technical word. In everyday speech it is mild and domestic, the word for a shelf put up straight or a table laid properly. But "nice" once meant precise, as in the phrase "a nice distinction," and that older sense still lingers here. The lungs feel pleasant and they feel exact, and the poem leaves both meanings in play. A casual adverb and a workshop term end up side by side, and neither sounds out of place.
The line breaks add further possibilities. Read as it falls on the page, "lungs / felt" can be a noun phrase for a moment, the fabric felt, soft and densely pressed. That reading doesn't last, because "nicely mitred" turns "felt" into a verb, but it flickers long enough to colour the picture with something muffled and packed. The verb itself is just as interesting. There is no "I" anywhere in the poem. Nobody is said to feel the lungs; the lungs themselves "felt," as if the body were sensing its own insides without a speaker standing between the reader and the sensation.
The sound and rhythm are very simple. There is no rhyme, but the words are linked by texture: the l and n sounds run through "lungs," "felt," "nicely" and even the nasal ending of "mitred" feels related. The two i vowels in "nicely" and "mitred," one long and one short, could be said to be the same sound cut at two different angles, which suits the joinery metaphor. With one word per line, the poem takes far longer to read aloud than its six syllables suggest. The two single-syllable lines, "lungs" and "felt," each get a full stress and a full pause, like slow breaths in and out. Then the lines widen to two syllables, both stressed on the first beat (NICE-ly, MI-tred), and the poem ends on the soft, unstressed "-tred," a small exhalation. The thin vertical column of words even looks like a narrow channel of air.
The poem has no story, speaker or argument. What it offers is a single sensation, held still and examined, and that is where its interest lies. It makes the reader notice something that normally happens below attention, and it does so by trusting that one precisely chosen word can carry more than a sentence of explanation. The poem is also, in a sense, mitred itself: each word is cut to size and joined to the next with no filler and no gap, which is the quality it praises in the lungs.
It is a good poem for testing your own reading. Swap "nicely" for "well," or "mitred" for "fitted," and see how much of the effect disappears. The answer shows how much work each word is doing.