Extended Metaphor

• Emily Dickinson's "Little Bird"
  
  "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)

This is an example of an extended metaphor.  How does the extended metaphor help convey the theme of the poem?

Create a theme statement and select three quotations to support your statement.