Answer: Love and longevity.
Explanation: Sonnet 18, which is titled Shall I Compare Thee To A Summer's Day, is a poem written by Williams Shakespeare and it is about love and longevity.
The poet in the poem compares a woman to a summer's day and says that while a summer's day contains defects, the woman has no defects.
He also says that the woman will live long.
The woman that the poet refers to can also be seen as a metaphor for the poem itself.