Continuing many of the images from Sonnet 64, the poet concludes that nothing withstands time's ravages. The hardest metals and stones, the vast earth and sea — all submit to time "Since brass, nor stone, nor earth, nor boundless sea, / But sad mortality o'er-sways their power." "O fearful meditation!" he cries, where can the young man hide that time won't wreak on him the same "siege of batt'ring days"?
In contrast to the previous sonnet, the poet once again is reassured that his sonnets will provide the youth immortality — his verse is the only thing that can withstand time's decay. Returning to the power of poetry to bestow eternal life, the poet asserts "That in black ink my love may still shine bright." He believes that his love verse can preserve the youth's beauty. Ironically, this back-and-forth thinking mirrors the movement of the waves to the shore — an image the poet uses in many of the time-themed sonnets in this sequence.
For example, in Sonnet 60, the poet says, "Each changing place with that which goes before, / In sequent toil all forwards do contend"; and in Sonnet 64, he notes, "Increasing store with loss and loss with store." Physically and emotionally separated from the young man, the poet's constantly shifting belief in the worth of his verse parallels his constantly shifting faith in the young man.