What does "insanity is relative. it depends on who has who locked in what cage." mean?

"Insanity is relative" - basically a metaphor for "insanity can only go so far" or something along those lines like "insanity can only be so sane"

"It depends on who has who locked in what cage" - Basically its saying who locked who in a cage, and are they a physco or what.

man that was confusing and this answer probably wont mean [email protected]#$ but i tried