“Sonnet 1” is a Shakespearean sonnet, also sometimes referred to as an English sonnet. Italian and English sonnets both have 14 lines, but the structure of the lines varies.

The overall architecture of a Shakespearean sonnet is three arguments (one developed in each quatrain) and a conclusion (the final couplet). “Sonnet 1” supports this structure with its rhyme scheme—ABAB CDCD EFEF GG—which divides the quatrains and the final couplet. After the three quatrains with alternating rhymes, the couplet with two adjacent rhyming lines offers a clear ending, or conclusion.

By contrast, Italian sonnets feature two sections, an octave (two quatrains) and a sestet (six lines), separated by a volta, or turn in the direction of thought. The octave has the set rhyme scheme ABBA ABBA, while the sestet has a variable rhyme scheme: CDE CDE or CDC DCD.

Shakespearean sonnets, meanwhile, can include multiple voltas. In “Sonnet 1,” the volta between the first and second quatrain is indicated by the conjunction “But” (Line 5). This word introduces a turn towards the specific—and childless—addressee of the poem, who is contrasted with the generic “fairest creatures” (Line 1) described in the first quatrain.