"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 -
The “Gale” is capitalised, the second abstract idea of the poem, representing the trials and storms that humans have to face.  It is at these moments that the bird’s song of Hope is “sweetest”. The implication is that the most turbulant times are alleviated by the metaphorical bird. 
 The use of stormy weather and elements to represent tubulant human lives is known as  pathetic fallacy . This device appears again in stanza three. 
 Dickension continues the dashes, mid as well as the end of the lines, building up certainty but with some remaining hesitation.
Hope is the thing with feathers