The three six-line stanzas of this poem all follow the same rhyme scheme and the same metrical pattern. There are only six rhyming sounds in this eighteen-line poem because the poem rhymes ababab, cdcdcd, efefef . The pairing of two rhyming sounds in each stanza works well because the poem concerns itself with the two forces—darkness and light—at work in the woman's beauty, and also the two areas of her beauty—the internal and the external. The rhyming words themselves, especially in the first stanza, have importance: notice how "night" rhymes with its opposites, "light" and "bright," in the same way that this woman contains the two opposing forces in her particular type of beauty. Oftentimes poets use their poetic structures to mirror what the poem's chief concerns are. Poetic form—stanzas and meter—and content—what the poem's subject is—are almost always related.

The meter...