Shakespeare and "Tradition": Passage of Poetic Craft and Art, Culture/Generation to Culture/Generation 

      Shakespeare wrote his sonnets long after the high point of the sonnet tradition.  Sidney's and Spenser's sonnet cycles had spawned numerous imitators, and practically every young poet who could hold a pen was cranking out fourteen lines of iambic pentameter rhyming in predictable quatrain/couplet combinations with tales of woe and intrigue about how badly their Beloveds were treating them (using Petrarchan conceits to exaggerate their pains) and how supernaturally beautiful their Beloved's were (using Petrarchan conceits to exaggerate their beauties).  Not infrequently, they wrote sonnets about nobody in particular, but rather they wrote because that was what young poets did in the late C16.  Think of the sonnet as the "blog" of Elizabethan England.  Not everybody was up to the job.  So when WS started writing them, he had to establish his sonnets' originality by contrasting them with others' work.  He also continued the tradition of "imitation with variation" by doing things done by Wyatt, Surrey, Sidney, and Spenser, but characteristically  by doing those things in ways his predecessors had never attempted.  Good as he is, though, even Shakespeare leaves traces of his mind's habitual concerns in the art he produces, though we cannot produce a biography from those traces.  Think of them as artistic "fingerprints," the signs of his personal style.