Wonderful images, thank you for sharing Sidestreet.
Not to belittle the art in the mosques, which looks like it would be truly enchanting in a 3D 360-degree full-scale rendering (aka real life), but rather to respond to the conception that the art "must have" been inspired by drugs, I'd like to share some of what I see here.
The patterns we see on the ceilings are characterized by simple geometrical shapes: circles and quadrangles. The complexity of the whole has a certain repetitive quality that suggests, perhaps, generation by iteration of a rule. What particularly suggests this to me is that these complex patterns are made up, if you look closely, of individual "bricks" that are in themselves extremely simple: colored rectangles of a consistent shape of size.
Once you're dealing with simple "units" such as these, application of mathematical formula can elegantly generate the complexity and beauty we see here. The formulas do not have to be complex, in fact they can even be discovered "spontaneously" y the designers without using mathematical notation, for example when the designer "sees" how various shapes can interlock to form a larger unit that is tileable, known in math as a tessellation.
My point is I feel that mathematics could be as likely an explanation as drugs for the extraordinary inspiration displayed here.
In fact, the similarity that these patterns have to drug visuals, looked at with the knowledge that these people very likely did not take drugs, suggests to me that mathematical functions may have a major role in the form that psychedelic visuals take.
In short, perhaps these artists (and perhaps those of the Hindu temples pharmer mentions, as well) discovered and were drawing on qualities inherent to the way nature works, qualities that also manifest in drug visuals (which are certainly a part of nature). This relationship does not necessarily imply a causal relationship (drugs caused the artwork). The idea of correlation vs. causation.
This is the point where I start thinking about chaotic attractors such as the Lorenz attractor, and the way that chaotic systems made up of completely different elements can tend to create the same patterns.
Edited by Cybilopsin, 14 November 2015 - 07:31 PM.