Donne opens as if in the middle of a thought, almost shrugging: "Twice or thrice had I loved thee, / Before I knew thy face or name." The speaker has loved a woman before meeting her, and the poem sets out to explain how that can happen and what love should do once it finds a real person. Its central idea is that love, however spiritual, cannot stay a vapour. It needs a body to live in, as an angel does, but it must not be weighed down by too much body.
The first stanza describes love without an object. The speaker met it in "a voice" or "a shapeless flame", the way angels "affect us oft, and worship'd be". When he finally came to where she was, he saw "some lovely glorious nothing", a phrase that holds a paradox. Something can be glorious and also nothing, and this is a feeling that has not yet found anything to attach to. Then the argument turns on "since". The soul's child, love, "takes limbs of flesh", and although it is "more subtile than the parent", it cannot exist unembodied. "And therefore" he allows love to settle in "thy lip, eye, and brow". The vocabulary of logic (since, therefore) gives the lines the air of a proof, though the tone is that of a lover who knows how neat his reasoning sounds.
The second stanza undoes that neatness with a joke. Body was meant to be ballast, something to steady the ship of love, but the speaker has loaded "love's pinnace", a small, light vessel, until it is "overfraught". The cargo "would sink admiration", and "admiration" here means something close to wonder. Physical detail, in other words, threatens to drown the very awe it was meant to support. The exaggeration is deliberate: "Ev'ry thy hair for love to work upon / Is much too much." The squeezed phrase "Ev'ry thy hair" sounds like a man staggering under his own freight. Having rejected "nothing" in the first stanza, he now rejects "things / Extreme, and scatt'ring bright", where beauty is scattered into too many glittering particles.
The solution is a middle path, borrowed from the angel in the title. An angel wears "face, and wings / Of air", which is "not pure as it, yet pure". Air is a body, but barely one. The speaker proposes that her love can be "my loves sphere", the element his love moves in and is clothed by, just as air clothes the angel.
The form follows the argument. Each stanza runs to fourteen lines, as long as a sonnet, and the second repeats the first's rhyme pattern almost exactly, so the stanzas read like proof and counter-proof. Lines swing between longer and shorter ones, and the short ones act as pauses. "I bid Love ask, and now" holds back before the permission arrives, and "Just such disparity" holds back before the comparison. Both stanzas end on a run of three rhymes, with *now / allow / brow* in the first and *disparity / purity / be* in the second. The final "be" also quietly answers the earlier "worship'd be", which ties the ending to the angels of the opening.
The last lines are the hardest. The gap between air and an angel's purity, we are told, is the gap "'Twixt women's love, and men's". The grammar never says which is which, but the poem's own logic casts his love as the angel and hers as the air that clothes it. That reading can sound condescending. It is also possible, judging by the playful ship image just before it, that Donne means the closing claim with a half-smile. The ending invites argument, and that may be part of its point.
The poem matters because it takes an old question, how spirit and body belong together in love, and refuses an easy answer. It does not praise pure souls or simple desire. Instead it makes a feeling think, with wit, a sinking ship and an angel in a coat of air, and it lets the speaker's cleverness show its seams.