I'm not sure how well proven it is, but the theory I saw for the common "sacred geometry" that people see while on psychedelics is that the brain normally is quite good at filtering out "noise" and the psychedelics limit this filtering. So, sacred geometry could be a type of noise produced by our biological hardware that the brain normally filters out as unnecessary. Other things besides psychedelics can cause these same patterns to be observed too, from what I understand.

Maybe not, I don't know. But at least we understand the pharmacology of many of them, which I guess is what I actually meant.