The Sonnet Form
The sonnet originated in thirteenth-century Italy; Petrarch, in the following century, inspired wide use of the form. Fourteen lines long and divided by the rhyme scheme (abbaabba cdecde) into an octave and a sestet, Petrarch's sonnets were addressed to an unapproachable woman in a sequence chronicling the author's changing psychological responses to the romantic relationship. The Petrarchan mode reached England by the early sixteenth century in the works of Wyatt and Surrey, who modified the sonnet by ending it with a rhymed couplet and by developing the rhyme scheme later adopted by Shakespeare (abab cdcd efef gg). In the 1590s, when Shakespeare was writing sonnets, the sonnet form was the height of literary fashion.
Although the vocabulary of Shakespeare's sonnets is usually simple, the metaphorical style is very rich. "Shall I compare thee to a summer's day" is a question that might lead to a very ordinary comparison, but instead it introduces a profound meditation on time, change, and beauty. The structure of a given sonnet frequently reinforces the power of the metaphors: for example, each quatrain in 73 develops an image of lateness, of approaching extinction- of a season, of a day, and of a fire- but they also apply to a life. In structural terms, the three quatrains may work equally and successively to prepare for a conclusion in the couplet (the so-called Shakespearean sonnet pattern), or the first eight lines may set forth a situation and the last six turn in quite a different direction (the usual Petrarchan structure). The rhetorical strategy of the sonnets is also worth careful attention. Some begin with a reminiscence, some are imperative, others make an almost proverbial statement and then elaborate it. The imagery is drawn from a wide variety of sources: gardening, navigation, religion, law, farming, business, pictorial art, astrology, and domestic affairs.