Blue! 'Tis the life of heaven,--the domain
Of Cynthia,--the wide palace of the sun,--
The tent of Hesperus, and all his train,--
The bosomer of clouds, gold, gray, and dun.
Blue! 'Tis the life of waters: -- Ocean
And all its vassal streams, pools numberless,
May rage, and foam, and fret, but never can
Subside, if not to dark-blue nativeness.
Blue! Gentle cousin of the forest-green,
Married to green in all the sweetest flowers,--
Forget-me-not,--the Blue bell,--and, that Queen
Of secrecy, the Violet: what strange powers
Hast thou, as a mere shadow! But how great,
When in an Eye thou art alive with fate!

John Keats

http://www.poemhunter.com/poem/sonnet-written-in-answer-to-a-sonnet-by-j-h-reynolds/