Prison bars

What can a prisoner say?
To bars he cannot escape.
I love you; but farewell,
I love you; but permit me, some leave!

Within his heart, yet, remains a serpent.
An unwelcome visitor sounds a hiss…
But unlike a stray-dog, he'll not bark nor
Snake through the undergrowth an adder?

So then Lord what is a key without a lock?
Or a jail without four walls…
Who turns the key to a door, without-walls?
To a door that's got no hinge.