That Perches in the soul

What does the exopression "That Perches in the soul" mean?

Thank you.

Why do you capitalize "perches"? It appears to be a verb (which one does not capitalize), and even if it were a noun, it's a common noun. The clause appears to mean, "that sits or rests in the soul." THe antecedent of the clause is something that takes a perch (a seat or a position a bit apart, in real life probably an elevated, sometimes precarious, position) in one's soul--something that stays with you in that place from which emanates the "still, small voice" telling you to do the right thing.
SS

I can't remember if Emily Dickinson capitalized Perches in the original manuscript, but the poem reads:

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.

Thank you very much for the explanations and particularly for the poem!