The poet John Keats, celebrated for his diverse literary creations, often grappled with the structural complexities of various poetic forms. Among these, the sonnet, with its rich historical lineage, presented a unique challenge. Keats's poem "On the Sonnet" reflects his engagement with this form, rooted in two predominant traditions: the Italian and the English.

The Italian sonnet, associated with luminaries such as Dante and Petrarch, is characterized by a clear division between an octave and a sestet. The octave typically follows an abba rhyme scheme, setting a foundation that demands precision and thematic development. This is followed by the sestet, which offers a measure of flexibility in its potential rhyme schemes, such as cde cde, cdc cdc, or cd cd cd. Despite the freedom within the sestet, the Italian form is constrained by its reliance on a limited number of rhyme sounds—four or perhaps five—and a stringent structural division of 8/6.

In contrast, the English, or Shakespearean, sonnet evolved to embrace a different configuration, utilizing a 4/4/4/2 pattern. This structure, which incorporates seven distinct rhyme sounds, is marked by its succession of three quatrains capped by a rhymed couplet (abab cdcd efef gg). Although this form offers more rhyming possibilities, Keats found the sharp conclusion of the final couplet somewhat jarring, as he expressed in a letter to his brother George in May 1819.

Keats's quest to balance the poetic constraints and creative expression led him to experiment with the sonnet's structure in "On the Sonnet." This poem showcases an unorthodox rhyme scheme of abc abd cab cde de, diverging from both the traditional Petrarchan and Shakespearean forms. By eschewing the typical octave and quatrain structures, Keats carved a new path, illustrating both his dissatisfaction with existing models and his inventive approach to poetic form.

In John Keats's exploration of poetic form, his sonnet "On the Sonnet" delves into the challenges and necessities of adhering to traditional stanza patterns and rhyme schemes. Keats's experimentation with these conventions paved the way for his celebrated odes of 1819, marking a pivotal moment in his literary journey, commonly referred to as his annus mirabilis. This period brought forth masterpieces such as “To a Nightingale,” “Ode on a Grecian Urn,” “Ode on Melancholy,” and “Ode on Indolence.” These works showcase the culmination of his innovative efforts. Keats's odes demonstrate how he preserved certain aspects of the sonnet forms while also transforming them. He retained the quatrain structure of the English sonnet (abab) and the sestet of the Petrarchan sonnet (cde, cde), yet he extended these forms to be more flexible and intricately interwoven. This approach allowed him to create poetry that more closely aligned with his artistic vision, making it a more intimate fit for "the naked foot of poesy." In his odes, Keats adeptly removed elements he regarded as "dead leaves" from the poetic form, thus avoiding monotony and embracing newfound creative freedom. This refinement of form culminated in the creation of the ideal genre he had envisioned in "On the Sonnet." His work in this period not only highlights his technical prowess but also his dedication to evolving poetic expression beyond conventional boundaries.