Emily Dickinson

They shut me up in Prose --
As when a little Girl
They put me in the Closet --
Because they liked me "still" --
Still! Could themself have peeped --
And seen my brain -- go round --
They might as wise have lodged a Bird
For Treason -- in the Pound --
Himself has but to will
And easy as a Star
Abolish his Captivity --
And laugh -- No more have I --

They shut me up in Prose --
Who is "they"? Why is Prose capitalized?

As when a little Girl
Why is girl capitalized?

They put me in the Closet --
Again, who is "they"? Why is Closet capitalized?

Because they liked me "still" --
Why is still put in quotations? Is this sarcastic? Which definition of still is she using here?

Still! Could themself have peeped --
Is the definition of still here different than the way it is used in the previous line?

And seen my brain -- go round --
Who is seeing her brain go round? Why does she use brain rather than mind, as usually one's mind will race or go round, while the brain is stationary in the head?

They might as wise have lodged a Bird
Why is bird capitalized here? Why is she comparing herself to a bird?

For Treason -- in the Pound --
In the pound does not seem to fit here, what is she saying here? Why is pound capitalized? How does a bird commit treason?

Himself has but to will
Who is himself?

And easy as a Star
Why is star capitalized? Why are stars easy? How are they easy?

Abolish his Captivity --
Who is holding him captive? Who will abolish this? Who is he?

And laugh -- No more have I --
What is the significance of her use of dashes? In this line and in the whole poem?