Hallucinogens have provided inspiration for artists long before the hippie revolution; prehistoric rock art depicting psychedelic mushrooms has been found and dated as around 8000 years old.
Ancient paintings have also been found and attributed to tribes associated with Datura, psychoactive cactus, and cohoba/yopo snuff.
Most importantly, some of these paintings also depict the elaborate geometric patterns familiar to anybody with experience in these psychoactives.
In the late 1950s, an artist was given a dose of LSD and access to art supplies as part of a government study. He documented his experience through a series of drawings: