Herrick's advice sounds friendly enough: pick the roses while they're fresh. But the cheerfulness gives way to arithmetic almost at once. By the second line, Time is "still a-flying", and "still" here carries its older meaning of "always", so the clock never pauses. By the fourth line, the flower that "smiles to-day" is already "dying". The title tells us the audience is young women, and the message is the classic *carpe diem*, seize the day, in its plainest form: youth is short, so use it.
What lifts the poem above a simple lecture is how carefully the case is built. It works like a small argument in four steps. The first stanza gives the command and one image, the rosebud. The second and third supply evidence, first from nature and then from human life. The fourth opens with a dash and a "Then", the point where the speaker says what follows from all this: "be not coy". Even the phrase "while ye may" comes back. It opens the poem and returns in the last stanza, so the whole piece is framed by a warning about a limited window.
The sun stanza is the most inventive. Herrick begins grandly, calling the sun "the glorious lamp of heaven", then turns it into a runner whose "race" must end. The logic is neat and a little unsettling: "The higher he's a-getting, / The sooner will his race be run." The sun's peak is the start of its descent. For a young reader, the lesson is that being at your brightest is exactly when the clock matters most. The homely "a-getting" and "a-flying" give the poem a folk-song swing, a spoken, unpolished quality that sits oddly and effectively beside the grand title for the sun.
In the third stanza the imagery drops away and the speaker states his view bluntly. Youth is when "blood" is "warmer", a physical, almost feverish picture of being alive. After that, life is "spent", a word that sounds like money running out. The decline is also built into the grammar. The sentence spills over the line break, "the worse, and worst / Times, still succeed the former", so the ranking of bad, worse and worst seems to tumble down the page. The word "still" appears again with the same meaning, a reminder that this process never stops.
The sound of the poem makes the same point. The rhymes follow an ABAB pattern, and the line lengths alternate between eight syllables and seven. The shorter lines always end on an unstressed syllable: "flying" and "dying", "getting" and "setting", "warmer" and "former", "marry" and "tarry". Those endings make the voice trail off, like a breath running out, while the longer lines end firmly on "may", "Sun", "first", "time". The metre is mostly a bouncy iambic beat, light enough to dance to. That is the poem's main trick: a sprightly tune carries a grim message, so the warning slips in almost unnoticed.
The final word deserves attention. "Tarry" is a gentle, slightly old-fashioned verb meaning to linger or wait, but placed after "for ever" it turns bleak. The person who loses her "prime" "but once", with that small word closing off any second chance, is left lingering indefinitely, as if stuck at a station after the last train. The practical advice, "go marry", is also telling. The poem's world treats youth as something with a shelf life, and a modern reader may find that assumption as interesting as the argument itself.
The poem matters because it does so much in sixteen lines of simple words. Most are one syllable, the images are things anyone has seen (a flower, the sun, a season of life), and the structure is clear enough to memorise. Yet it holds a very old idea, that time is both our scarcest resource and the thing we waste most easily, in a form that stays in the ear. It persuades by charm first and by fear second, and that mixture is why it still works.