Extended Metaphor

Extended Metaphor: A metaphor developed at length, ocurring frequently in or throughout a work. 

Example:
"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 strongest sea;
Yet, never, in extremity,
It asked a crumb of me."

(Little Bird, Emily Dickinson)

This is an example of extended metaphor because it compares many things to the little bird. Throught the whole poem she compares the bird to many things without actually saying it's a bird.