like the brain is literally encased in the body so how can it be separate? like if you go around licking lamp posts you’re going to pick up some germ that’s gonna make you feel like crap and you get insomnia or fever and your brain will definitely be impacted. and so you’ll have short temper and that’ll get you into trouble.
It’s because of mind-body dualism. Most people have absorbed some amount of mysticism from the culture around them without realizing it, and a distressing amount of Western mystic traditions have some form of mind-body or spirit-body dualism.