In total, Shakespeare wrote 154 sonnets, which were published in 1609. Of these 154 poems, only the last 25 are considered the “Dark Lady” sonnets, which “Sonnet 129” is part of. Introduced just two sonnets before this one, the Dark Lady is a mistress of the speaker who contrasts with the Fair Youth, the subject of most of the sonnets up to this point. In this early sequence of Dark Lady sonnets, the speaker describes the unconventional beauty of the woman, in what may often seem like unflattering terms. Despite this, the speaker feels intense sexual desire for the woman, leading to feelings like jealousy.

The sonnet was a popular poetic form in England for two centuries before Shakespeare adopted it. The form was first popularized in Italy by the poet Petrarch, and later adapted by the English poets Sir Thomas Wyatt and Henry Howard, Earl of Surrey. Sonnets in the Petrarchan tradition were usually about love—often an unrequited love for a highly idealized and unobtainable woman. The beloved woman was often described using a blazon, or a list of the woman’s desirable physical and personal attributes, depicted in elaborate metaphors and similes. The speaker in the Petrarchan-style sonnet would often dwell upon the torments of his unfulfilled passion, while also admiring the beloved lady’s beauty, chastity, and apparent perfection.