Not marble, nor the gilded monuments (1): This line is likely an allusion to the lavish tombs of English royalty; in particular, to the tomb of Henry VII in Westminster Abbey, which contains a large sarcophagus made of black marble with gilded effigies of King Henry and his queen, Elizabeth of York. unswept (4): note that the pronunciation here is /UN swept/. with sluttish time (4): i.e., by filthy time.
In Elizabethan England the word "sluttish" could describe either a sexually promiscuous woman or a grubby, unkempt woman. Here Shakespeare personifies Time as the latter. broils (7): angry, violent quarrels or riots. all-oblivious enmity (9): i.e., the war and decay that would render the subject of the poem forgotten.
Sonnet 55 is one of Shakespeare's most famous works and a noticeable deviation from other sonnets in which he appears insecure about his relationships and his own self-worth. Here we find an impassioned burst of confidence as the poet claims to have the power to keep his friend's memory alive evermore.
Some critics argue that Shakespeare's sudden swell of pride in his poetry was strictly artificial - a blatant attempt to mimic the style of the classical poets. "It is difficult on any other hypothesis to reconcile the inflated egotism of such a one as 55 with the unassuming dedications to the Venus and Lucrece, 1593 and 1594, or with the expressions of humility found in the sonnets themselves, e.g. 32 and 38" (Halliwell-Phillipps, 304).
However, many believe that such an analysis ignores Shakespeare's paramount desire to immortalize his friend in verse, and not himself (as was the motive of most classical poets). "The Romans say: Because of my poem I will never die. Shakespeare says: Because of my poem you will never die....What distinguishes Shakespeare is that he values the identity of the beloved; he recognizes that the beloved has his own personal immortality, in no way dependent on poetry" (Martin, 158). By focusing on the word