In the plays written before Romeo and Juliet, Shakespeare had already feasted on the banquets the English language afforded, especially in Love's Labour's Lost ( 1595), but his appetite (to paraphrase Enobarbus on Cleopatra's effect) seemed to grow by what it fed on. Throughout his career, as many commentators have remarked, he constantly pushed the resources of his primary medium--words--to their utmost boundary, both in verse and in prose. Romeo and Juliet is one of the best examples of how he adapted English drama to the love poetry of his time and place, particularly the kind of poetry he had already developed and continued to develop in his long erotic narrative poems, Venus and Adonis ( 1593) and The Rape of Lucrece ( 1594), and in his sequence of sonnets, which circulated among his friends but was not published until 1609.
As if to prepare his audience for part of what was to come, Shakespeare began Romeo and Juliet with a sonnet-speaking Chorus, or Prologue, using the form he had also used for his sonnet sequence, rather than the Italian form Petrarch used; that is, three quatrains followed by a couplet, instead of an octet rhyming abba abba, followed by a sestet. 1 Petrarch, however, is otherwise much in evidence, especially in the first half of the play. Romeo's infatuation with Rosaline inspires the purest Petrarch, moving Mercutio to salute him with "Now is he for the numbers that Petrarch flowed in" (2.4.34). Although by then the taunt is no longer relevant, Mercutio does not know this; he is reacting to the Romeo who, in his first dialogue with Benvolio, unabashedly apes the Petrarchan "numbers." His lines there typify the conventional lover's versifying, complaining of the treatment by his Cruel Mistress: