Hope is the thing with feathers 
That perches in the soul, 
And sings the tune without the words, 
And never stops at all, 
 
And sweetest in the gale is heard; 
And sore must be the storm 
That could abash the little bird 
That kept so many warm. 
 
I've heard it in the chillest land, 
And on the strangest sea; 
Yet, never, in extremity, 
It asked a crumb of me.
Emily Dickinson
http://www.poemhunter.com/poem/hope-is-the-thing-with-feathers-2/