Shakespeare's sonnets comprise 154 poems in sonnet form that were published in 1609 but likely written over the course of several years. Evidence for their existence long preceding publication comes from a reference in Francis Mere's 1598 Palladis Tamia, Wits Treasury, where his allusion to Shakespeare's "sugred Sonnets among his private frinds" might indicate that the poet preferred not to make these works public. It is unclear whether the 1609 publication, at the hands of a certain Thomas Thorpe, was from an authorized manuscript of Shakespeare's; it is possible that the sonnets were published without the author's consent, perhaps even without his knowledge.
This is but one of the mysteries of Shakespeare's sonnets. Another, which continues to spur debate among literary scholars today, is the identity of the publication's dedicatee, the collection's "onlie begetter," a Mr. W. H. Speculation largely vacillates between two main candidates: Mr. William Herbert, third Earl of Pembroke; and Mr. Henry Wriothesley, third Earl of Southampton. Both possibilities are tenable, as both were men of means and of literary interest enough to be patrons to Shakespeare. In fact the poet dedicated other works to each: his First Folio to Herbert and his Venus and Adonis and Lucrece to Wriothesley. Those who favor one man or the other draw on circumstantial evidence concerning his life and character, such as the amicable terms on which Shakespeare is known to have been with Wriothesley, or events in Herbert's life that may be intimated in the exploits of the sonnets' "fair lord."
The fair lord is one of three recurring characters in the sonnets, together with the dark lady and the rival poet. The real-world referents of these persons are yet another locus of controversy. Some critics suggest that the fair lord and the collection's dedicatee are one and the same, while others disagree. Still others question the autobiographical nature of the sonnets, arguing that there is no hard proof that their content is anything but fictional.
These mysteries and others, including the ordering of the sonnets, the date of their composition, and seeming deviations from the otherwise rigid format (one sonnet has 15 lines, another only 12; sonnets 153 and 154 do not fit well in the sequence), have generated an abundance of scholarly criticism over the years, and the dialogues they provoke remain highly contentious to this day.
The 1609 publication of Shakespeare's sonnets is today referred to as the "Quarto" and remains the authoritative source for modern editions.