What is a summary of Sonnet 18?
In this sonnet, structured according to the Shakespearean (rather than the Petrarchan) rhyme scheme, the speaker questions whether he should compare his lover "to a summer's day." He decides, however, that the comparison would be ill-fitting, because his lover is both "more lovely and more temperate."
The speaker goes on to identify various elements which make summer less lovely than the subject of the poem. Summer can be subject to "rough winds," and "summer's lease" is short. Sometimes the sun ("the eye of heaven") can be too hot in summer; likewise, the sun is "often...dimm'd." Everything that is "fair from fair sometime declines" with the passage of nature.
By contrast, the speaker says, the "eternal summer" of his beloved "shall not fade." He declares that unlike summer, which passes away into autumn as a natural consequence of time moving on, his beloved will never wander in the "shade" of death. Instead, the "eternal lines" of the poem will live on beyond either its author or its subject. "So long as men can breathe or eyes can see," the subject of the poem will live because the poem itself will endure. As such, his lover is entirely unlike summer, which can only last for a brief space.
check Approved by eNotes Editorial