How can a bird that is born for joy Sit in a cage and sing? - William Blake

Then cherish pity, lest you drive an angel from your door.

"Piping down the valleys wild
Piping songs of pleasant glee
On a cloud I saw a child.
And he laughing said to me.

Pipe a song about a Lamb;
So I piped with merry chear,
Piper pipe that song again — So I piped, he wept to hear.

Drop thy pipe thy happy pipe
Sing thy songs of happy chear,
So I sung the same again
While he wept with joy to hear

Piper sit thee down and write
In a book that all may read — So he vanish'd from my sight.
And I pluck'd a hollow reed.

And I made a rural pen,
And I stain'd the water clear,
And I wrote my happy songs
Every child may joy to hear.

- "Introduction to the Songs of Innocence

And did the Countenance Divine,
Shine forth upon our clouded hills?
And was Jerusalem builded here,
Among these dark Satanic Mills?