The poem has a loose, flexible structure, incorporating stanzas of different lengths, as well as single lines and two-line sections. The lines vary greatly in length, from one poetic foot (two syllables) to seven poetic feet. The first three stanzas are quatrains; the two stanzas that make up lines 19 to 30 are sestets (six lines each). They are followed by an eight-line stanza and then a 12-line stanza, the longest in the poem. Line 51, consisting of just two words, is followed by a 10-line stanza (Lines 52-61), then an eight-line one (Lines 62-69), then two five-line stanzas, followed by a seven-line stanza that concludes the poem. There are in total three single lines standing apart from the stanza structure, one rhyming couplet (Lines 15-16) and one two-line, italicized section set apart (Lines 17-18). Overall, the variable stanzaic structure gives the impression of an improvisational jazz piece rather than something that follows traditional poetic form.

Within that irregular structure, however, many of the lines are iambic pentameters, a common poetic form. An iamb is a poetic foot consisting of an unstressed syllable followed by a stressed syllable. The stanza that makes up Lines 39-50, for example, has many iambic pentameters, such as “Who dreamt a dream so strong, so brave, so true” (Line 41), and the following four lines: