The lines of Satan in Book I "The mins is its own place, and in itself can make a heaven of hell, a hell of heaven" is explained and compared below
Explanation:
The line is "The mind is its own place, and in itself can make a Heav'n of Hell, a Hell of Heav'n."
The first line explains that the mins is its own place this is the place where the mind stays and works (thinks) and because mind have so much power of thinking that just by thinking the mind can change any situation, by thinking negatively a mind can change a heaven into hell and by thinking so much positively a mind can change a hell into heaven.
