This poem repeats the theme of others, notably sonnet 18, that the poem itself will survive human mortality, and both the poet and Fair Youth will achieve immortality through it. In this case all the hazards of an unpredictable future are added to the inevitability of mortality.
The line about the eclipse of the moon has sometimes been interpreted as reference to death of Queen Elizabeth I
Sonnet 107 can also be seen as referring to Doomsday. The sonneteer's love cannot even be ended by the "confined doom." The eclipse of the moon, then, like the "sad augurs," refers to a sign that might presage the Last Judgment. While everything else (the "tombs of brass" for example)comes to an end, the "poor rhyme" will be the last thing to go. As in Sonnet 55, the power of the sonnet to give life to the young man -- or, here, to serve as a monument to him -- will only be overshadowed when that young man literally comes forth from the grave on Judgment Day.