The Doors of Perception and Heaven and Hell

I enjoyed the Heaven and Hell more than The Doors of Perception. While an interesting take on the psychedelic experience, it was the the ponderings about religion, of aesthetics like stained-glass windows of the cathedrals, the incense, the ritual chants that transfer us into different realities, that I found thoroughly enlightening.

There are a lot of cultural references here, and having read into Joseph Campbell's work, Zen and Meister Eckhart made this much more easily approachable than what it would've been without that pre-existing knowledge.