A
The form of lyric poetry known as the sonnet, or “little song,” was introduced into the English poetic corpus by Sir Thomas Wyatt the Elder and his contemporary Henry Howard, Earl of Surrey, during the first half of the sixteenth century. It originated, however, in Italy three centuries earlier, with the earliest examples known being those of Giacomo da Lentini, “The Notary,” in the Sicilian court of Emperor Frederick II, dating from the third decade of the thirteenth century. The Sicilian sonneteers are relatively obscure, but the form was taken up by the two most famous poets of the Italian Renaissance, Dante and Petrarch, and indeed the latter is regarded as the master of the form.

B
The Petrarchan sonnet form, the first to be introduced into English poetry, is a complex poetic structure. It comprises fourteen lines written in a rhyming metrical pattern of iambic pentameter, that is to say, each line is ten syllables long, divided into five feet or pairs of syllables (hence “pentameter”), with a stress pattern where the first syllable of each foot is unstressed and the second stressed (an iambic foot). This can be seen if we look at the first line of one of Wordsworth’s sonnets, “After-Thought”: “I thought of thee my partner and my guide.” If we break down this line into its constituent syllabic parts, we can see the five feet and the stress pattern (in this example, each stressed syllable is underlined): “I thought / of thee / my part / ner and / my guide.”

C
The rhyme scheme for the Petrarchan sonnet is equally rigid. The poem is generally divided into two parts, the octave (8 lines) and the sestet (6 lines), which is demonstrated through rhyme rather than an actual space between each section. The octave is usually rhymed abbaabba, with the first, fourth, fifth, and eighth lines rhyming with each other, and the second, third, sixth, and seventh also rhyming. The sestet is more varied: it can follow the patterns cdecde, cdccdc, or cdedce. Perhaps the best interpretation of this division in the Petrarchan sonnet is by Charles Gayley, who wrote: “The octave bears the burden; a doubt, a problem, a reflection, a query, an historical statement, a cry of indignation or desire, a vision of the ideal. The sestet eases the load, resolves the problem or doubt, answers the query or doubt, solaces the yearning, realizes the vision.” Thus, we can see that the rhyme scheme demonstrates a twofold division in the poem, providing a structure for the development of themes and ideas.

D
Early on, however, English poets began to vary and experiment with this structure. The first major development was made by Henry Howard, Earl of Surrey, altogether an indifferent poet, but was taken up and perfected by William Shakespeare, and is named after him. The Shakespearean sonnet also has fourteen lines in iambic pentameter, but rather than the division into octave and sestet, the poem is divided into four parts: three quatrains and a final rhyming couplet. Each quatrain has its own internal rhyme scheme, thus a typical Shakespearean sonnet would rhyme abab cdcd efef gg. Such a structure naturally allows greater flexibility for the author, and it would be hard, if not impossible, to enumerate the different ways in which it has been employed, by Shakespeare and others. For example, an idea might be introduced in the first quatrain, complicated in the second, further complicated in the third, and resolved in the final couplet—indeed, the couplet is almost always used as a resolution to the poem, though often in a surprising way.

E
These, then, are the two standard forms of the sonnet in English poetry, but it should be recognized that poets rarely follow rules precisely, and a number of other sonnet types have been developed, playing with the structural elements. For instance, Edmund Spenser, more famous for his verse epic The Faerie Queene, invented a variation on the Shakespearean form by interlocking the rhyme schemes between the quatrains, thus: abab bcbc cdcd ee. Meanwhile, in the twentieth century, Rupert Brooke reversed his sonnet, beginning with the couplet. John Milton, the seventeenth-century poet, was unsatisfied with the fourteen-line format and wrote a number of “Caudate” sonnets, or sonnets with the regular fourteen lines (on the Petrarchan model) with a coda or tail of a further six lines. A similar notion informs George Meredith’s sonnet sequence Modern Love, where most sonnets in the cycle have sixteen lines.

F
Perhaps the most radical of innovators, however, has been Gerard Manley Hopkins, who developed what he called the “Curtal” sonnet. This form varies the length of the poem, reducing it in effect to eleven and a half lines, the rhyme scheme, and the number of feet per line. Modulating the Petrarchan form, instead of two quatrains in the octave, he has two tercets rhyming abc abc, and in place of the sestet, he has four and a half lines, with a rhyme scheme dcbdc. As if this is not enough, the tercets are no longer in iambic pentameter but have six stresses instead of five, as does the final quatrain, except for the last line, which has three. Many critics, however, are sceptical as to whether such a major variation can indeed be classified as a sonnet, but as verse forms and structures become freer, and poets less satisfied with convention, it is likely that even more experimental forms will out.