Herrick asks for a miracle and a lullaby in the same breath. In eight lines he speaks directly to music, addressing it as "Charms", and tells it to take a suffering young man, send him to sleep, and return him to the world renewed. We learn nothing about what ails him. The title's "sweet sick youth" is all we get, and the poem does not need more. Its central idea is that music is a kind of gentle magic, strong enough to move the heavens yet delicate enough to be trusted at a sickbed.
The first line sets the scale. Music can "call down the moon from out her sphere", an image that recalls the old picture of the heavens as nested spheres and the long tradition of enchantresses summoning the moon. Then the poem shrinks abruptly. By the next line we are at a bedside, with "this sick youth" and "here". The move from the cosmos to one patient in a single couplet shows how the poem sees music's power: vast in range, but aimed at one person.
The verbs do the work of a charm. Music is told to "work", "bind up", "fall", "keep". "Bind up" has a double sense, since it can mean bandaging a wound or tying someone with a spell. "Numbers" was a common word in Herrick's time for verses and musical measures, so music and poetry blur together. The poem is itself a set of numbers, a small charm trying to do what it asks for. "Entrance" is both a verb meaning "put into a trance" and a hint of delight. The request is also modest. Music is asked "to entrance his pain, *or* cure his woe". Numbing the pain would be enough, and the "or" admits that a full cure may be too much to ask.
The second half softens the sound. "Fall gently, gently" repeats the word and slows the line almost to a whisper. The verb "fall" also echoes the moon that was called down in line one, so the great celestial power is now asked to descend as softly as a blanket. The most striking phrase is "the civil wilderness of sleep". A wilderness is wild and easy to get lost in, and the youth is indeed "lost" there. But "civil" means orderly and well-mannered, so this is a tamed wilderness, a place where one can wander safely. The oxymoron captures sleep's strangeness and its kindness together. Then "dispossess'd of pain" treats the illness like an unwelcome tenant or spirit, something to be moved out so that the youth owns himself again.
The form supports this calm. The poem is four rhyming couplets in iambic pentameter: sphere/here, so/woe, keep/sleep, pain/again. Each rhyme closes with a soft click, like a door shut quietly on a sleeper. Herrick loosens the pattern slightly in places. "Bind up his senses with your numbers, so / As to entrance his pain" spills over the line break, as if awareness were slipping away mid-sentence. The turn at "That done, then" marks the shift from putting the youth to sleep to waking him. Nearly every sentence is a command until the last, where the voice relaxes into "let him". The final rhyme, "pain" with "again", is neat, because the word that returns the youth to himself sits exactly where the pain is named and left behind.
The ending is the poem's most surprising choice. We might expect the youth to wake "healed" or "well". Instead he wakes "like to a slumbering bride". The simile suggests freshness, colour and anticipation, and judging by the imagery, sleep has made him lovelier rather than weaker. It also explains the title's "sweet", since the patient is someone whose recovery is imagined as a kind of beauty.
What makes the poem worth reading is how much it does in so little space. It is a prayer, a spell, and a piece of music in its own right. It also reflects a belief that sound and verse could act on the body and mind, and it states that belief with grace and without fuss.