I'm sure there's an echo of Hughie the Graeme in the Ballad of Serenity. Compare:

"Peace, be still, my father dear,
All your grieving, let it be,
Though they bereave me of my life
They cannot take the heavens from me."

"Take my life, take my land
Take me where I cannot stand.
I don't care, I'm still free:
You can't take the sky from me,"

Whedon's 'sky' means something different from HtG's 'heavens', but the sentiment's very similar.