Satan is so bad-ass in the first book of Paradise Lost. He wakes up in hell and struts out the pithiest of sayings. Like,
Hail Horrours, hail
Infernal world, and thou profoundest Hell
Receive thy new Possessor: One who brings
A mind not to be chang’d by Place or Time.
The mind is its own place, and in it self
Can make a Heav’n of Hell, a Hell of Heav’n.
(Bk. I, 250-255)
Boom! Drops the mike. On he goes, immutable God of his own internal state, right?
But when he leaves hell and the fawning gazes of his co-conspirators, he has a moment where he is more honest with himself. He gets depressed, surrounded yet untouched by the awesomeness of Eden, because
within him Hell
He brings, and round about him, nor from Hell
One step no more then from himself can fly
By change of place
(Bk. IV, 20-23)
And he eventually realizes,
Which way I flie is Hell; my self am Hell;
Poor devil. He thinks his strength is in a mind that refuses to change. But a mind that cannot change is unnatural and ill-fitting in a world where change is the only constant. He is right that the mind is its own place. But the mind that refuses to change will more likely turn heavens in hell.