A wish opens the poem, and it never settles into a complete sentence: "If one could have that little head of hers / Painted upon a background of pure gold!" The exclamation mark gives it away. The speaker sounds like a connoisseur thinking aloud, half to himself and half to a listener ("you'd see this sweet face by"), planning a portrait he cannot commission. The poem is about more than painting, though. Its real subject is a face so remarkable that rival schools of art, and finally heaven itself, can only stop and stare.
The speaker's first plan is the flat, glowing gold ground of early Tuscan painting, with the head isolated in profile and "no shade encroaching." The words he chooses, "pure," "matchless," "perfect," belong to worship. His instructions are oddly strict. He wants her lips "opening soft," but "not as when she laughs, / For that spoils all." That is a little unsettling. The living woman laughs, and the ideal woman must hold still. Even so, the picture he builds is sensuous. A hyacinth she loves leans toward her mouth, its "honey-colored buds" echoing the gold of the background, as though the flower and the painting were made of one material. Then come "three fingers" around the neck and a chin "fruit-shaped" and ripe. His hand has already started to touch the portrait.
Then he interrupts himself: "I know, Correggio loves to mass, in rifts / Of heaven, his angel faces." The conversational "I know" shows him anticipating an objection from someone who prefers a softer, more crowded style. In that style the faces are piled "orb on orb," their outlines broken, with shadows that "burning shades absorb." The rhyme of "orb" and "absorb" makes the angels seem to dissolve into one another. Here the poem turns. Instead of choosing between the two methods, the speaker reinterprets the second. Those massed angels, he says, are "only massed there, I should think, / Waiting." They are an audience. The modest "I should think" is charming, because he offers a bold claim about the whole of heaven as if it were a guess.
What they wait for is her. The verbs "grow out, stand full, fade slow" trace a wonder arriving, peaking and departing, and the odd adverb "momently" stretches the arrival over moments we can almost count. The sky behind the face becomes the "pale ground" he asked for at the start, so heaven now plays the part of the gold. The final image pulls the whole crowd of angels into a single watching eye, "all heaven, meanwhile, condensed into one eye / Which fears to lose the wonder, should it wink." The poem ends on a held breath. The smallest human reflex, a blink, threatens to make the miracle vanish.
The form moves along with this. The opening lines rhyme in tidy alternation (hers / gold / prefers / mould), and the next four are looser, with "laughs" and "staff's" only a near-match. After that the poem tightens into couplets (kiss / this, surround / ground, lifts / rifts, orb / absorb) and ends on a triple rhyme, "sky," "by," "eye." "Think" and "wink" frame that stretch, and "momently" has no rhyme partner at all, which suits a word about suspended time. The lines are mostly iambic pentameter, but the sentences spill over their endings ("aloft / Yon hyacinth"), so the verse keeps leaning forward like the hyacinth toward her lips. The rhythm is flowing, even as the subject is a still picture.
The poem matters because it dramatizes the old rivalry between capturing a person and loving one. The speaker cannot decide whether she belongs in a frame, and the poem's answer is that no frame is big enough. Browning wrote poems about painters elsewhere, such as "Fra Lippo Lippi" and "Andrea del Sarto," but here the artist is only imagined, and the finished picture is the poem. In twenty-two lines, an affectionate and slightly comic wish turns into a vision in which the whole sky holds its breath to look at one small, laughing, unpaintable face.