The poet writes his beloved's name «upon the strand», and the wave washes it away; he writes it again, and the tide makes his pains its prey. She chides him: it is vain to immortalize «a mortal thing», for she, like that name, will one day decay too.
He answers that it is not so: let baser things die in the dust — she shall live by fame, eternized in his verse. The sonnet fulfils itself — the poem that promises immortality is already the immortality it promises — and it closes in serene faith: when death has subdued all the world, «our love shall live, and later life renew».