How shakespeare immortalize his friend in sonnet 18?

Answer:
By comparing him to a summer's day. Really. The point of the poem is that the handsome young man would become old and ugly within 50 or 60 years, but if Shakespeare wrote a poem about him, people would remember his beauty for 400 years or more. And by Gadfrey he was right!
First answer by Bolognaking. Last edit by Bolognaking. Contributor trust: 239 [recommend contributor recommended]. Question popularity: 1 [recommend question].