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 —
Caudate sonnet is one of many in which Hopkins experimented with variations on sonnet form. However, unlike the curtal sonnet, a Hopkins invention which is a 10½-line form with precisely the same proportions as a Petrarchan sonnet, his caudate sonnet is a full sonnet unmodified but with an extra six lines. Hopkins heightens the effect of the extension with an enjambment from the 14th line to the 15th. Hopkins explored the possibility of such a coda in a series of letters exchanged with Robert Bridges, from whom he learned of the centrality of Milton's example in the form. Though the intent of