GOD guard me from those thoughts men think
In the mind alone;
He that sings a lasting song
Thinks in a marrow-bone;
From all that makes a wise old man
That can be praised of all;
O what am I that I should not seem
For the song's sake a fool?
I pray -- for word is out
And prayer comes round again --
That I may seem, though I die old,
A foolish, passionate man.

William Butler Yeats

http://www.poemhunter.com/poem/a-prayer-for-old-age/