This poem by William Shakespeare compares the beauty and qualities of the person addressed to a summer's day. It suggests their beauty is more enduring and constant than the fleeting nature of summer days or seasons that change over time. Through metaphors and nature imagery, the poem implies the person will remain beautiful and their relationship will stand the test of time, outlasting mortal decay. The poem uses literary devices like metaphor, personification and rhyme to praise the subject's eternal and immortal beauty.