Both traditional and modern Shakespeare critics are united upon one point in their respective and various appraisals of the sonnets: the quality of the sonnets is highly variable. Among the 154 verse pieces included in the 1609 edition of Shakespeare's sonnets, at least one (Sonnet 145, the only one in the entire collection written in tetrameter) is universally considered to be so poor that its authenticity as the work of the Bard has been repeatedly questioned. Perhaps Shakespeare merely had a bad day on Sonnet 145, or, just as plausibly, published and arranged a dozen odd years after they were written, this piece may be the handicraft of another (and far lesser) poet. Here we must mention that the last two sonnets in the 1609 edition (153 and 154) are radically different from the other works, having an explicit literary source in Ovid's Metamorphoses. Their authenticity has also been challenged: it is plausible that the publisher of the first edition tacked on two sonnets by another author, hitching the latter to the star of Shakespeare's lofty reputation.
These minor enigmas aside, while the extent to which Shakespeare's name has become virtually synonymous with romantic poetry is not fully measured by his sonnets, this set contains some of the finest examples of Shakespearean love poems. The Exemplary Sonnets section focuses upon three outstanding pieces: Sonnet 18, ("Shall I compare thee to a summer's day"); Sonnet 55, ("Not marble, nor the gilded monuments"); and Sonnet 138, ("When my love swears that she is made of truth") from the Dark Lady set.