Sonnet 30 up of fourteen lines in three quatrains and a couplet, rhyming "abab cdcd efef gg". While using the rhyming and metrical structure of the 'English' or 'Surreyan' sonnet, Shakespeare often also reflected the rhetorical form of the Italian form also known as the Petrarchan sonnet. It divides the sonnet into two parts: the "octet" (the first eight lines) usually states and develops the subject, while the "sestet" (the last six lines) winds up to a climax. Thus a change in emphasis, known as the "volta", occurs between the end of the eighth and the beginning of the ninth lines —
Sonnet 151 steer his actions. It uses the body as a metaphor for the penis, "rising" and "falling" with an erection when aroused, and so reduces the speaker to nothing more than his phallus; by giving in to his desires he enslaves himself to the "Dark Lady". Sonnet 151, with a "bawdy chronicle of erection and detumescence," contrasts with Sonnet 55's "grandiloquent expression," but their theme is the same: "what changes, what remains." Sonnet 55 "celebrates ... love and poetry that endure[s]" where Sonnet 151 "contemplates the inevitability of change..." Sonnet 151 has been compared to a verse by 17th-century author Joseph