The Geometric Model
Terence McKenna, Imagination In The Light Of Nature
I've come to what I call the "geometric model of the psychedelic experience." I certainly don't represent it as the end of the intellectual road, but it is a provisional model which is the best I can do at the moment. I think that, and it seems logically compelling to me, that consciousness as ordinarily experienced is a human ability shaped by evolutionary pressure, and since evolutionary threat and harm usually comes at us in three dimensional space, this is where consciousness has been forced...to concentrate and define itself.
Let me restate it.
Because of the possibility of being stepped on by woolly mammoths and eaten by sabre-tooth tigers, the primitive evolving mind of human beings concentrated on nearby space and time because that's where threat comes from, the kind of threat that has to be immediately responded to by running away or fighting or something like that. But...if the psychedelics prove anything they prove that consciousness is an incredibly plastic and malleable medium. So what happens when you take a compound like psilocybin in silent darkness in a situation of no threat and low anxiety and low input from the exterior world is that this function, which is essentially in most situations a closed fist ready to strike out at something coming from nearby, unfolds into something much more beautiful, much more interesting, and much more true to itself. In other words, not defined by an exterior context or situation, but defined by its own mechanics.
» Nick Herbert and Max face the Quantum Facts