Moonlight, a harp and a crowd of young people who cannot keep still: that is the whole scene, and Moore spends two stanzas making it feel like the most natural thing in the world. The speaker is a sort of master of ceremonies, ordering the musicians ("Strike the gay harp!", "Again! Again!") and coaxing the hesitant onto the floor ("Why then delay"). The central idea is that music and youth together make a force almost impossible to resist, one that reaches from human hearts to statues, stars and even Death itself.
The opening shows how Moore frames dancing as something closer to a law of nature than a choice. Young hearts are "as true to her beam as the tides of the ocean", and the verbs that follow, "obey" and "heave into motion", belong to water pulled by the moon. The moon's summons is "mute", so there are really two calls: a silent one from the sky, then the harp. Dancing here is not something the young decide to do. It happens to them.
From there the poem escalates. First come statues. The speaker borrows a "City of Statues described by romancers", a place from storybooks, and imagines the music so powerful that "statues themselves all start into dancers". The rhyme of "romancers" with "dancers" delivers the joke neatly, and "start" works twice, meaning both "begin" and "leap up". In the second stanza the stars "leave the song of their spheres" to listen. This refers to the old idea that the heavens make their own music as they turn, so human music is imagined as outdoing the cosmos, with the stars "hang[ing] wondering o'er us". The boldest step is the line about Death, whose "cold pulses" might be set "bounding". Death has no pulse to speak of, so the line is a small paradox, and the poem hints that dancing is a kind of defiance of mortality. It is also the only moment of shadow in the poem, and it is there only to be overpowered.
The construction does much of the work. Each stanza has eleven lines in the same pattern: a quatrain rhymed abab, a rhyming pair, the refrain "Again! Again!", and a closing quatrain, again abab. The rhythm is a lilting, three-beat one, with two unstressed syllables slipping between the stresses, which gives a skipping motion. Many of the rhymes are two-syllable ones: "ocean" and "motion", "lightest" and "brightest", "sounding" and "bounding", "feather" and "together". That extra soft syllable acts like a foot springing off the floor. The refrain is the sharpest change of pace. It cuts the line short, like the pause before the band starts again, and it makes the poem an encore in progress. Judging by its direct commands to musicians and its repeated cry, it reads like a lyric made to be sung.
The ending turns the poem's attention from the cosmic back to the human. The dancers have "eye like a sunbeam and foot like a feather", one simile for light and one for weightlessness. They move "like the Hours to the music of May", so time itself is pictured as a dancer, and the final line mixes "sweet song and sunshine together". This is a surprise in a poem about a night dance. It begins under moonlight, but by the close the young people seem to carry their own daylight. The moon starts the dance, and the dancers end up supplying the brightness.
The poem is worth reading for its unembarrassed delight. There is no irony and no hedging, just a speaker who wants the music louder and the dancing faster. Moore is known as a writer of song lyrics, and "The Night Dance" shows why. The sound carries the meaning, and the rhythm gets the reader moving before the argument has been understood.