There were apparently many who went to see this in cinemas in 1968 who were under the influence of illegal substances because it was supposed to be even more trippier - like the infamous stargate ot starfield section. Technically it's a stunning film, but on drugs? It's actually bloody bleak and I'd guess induced a few bad trips!
Is that right? I read somewhere that a bunch of heads (from San Francisco, probably) said that if you saw this film on acid, then it would be The Ultimate Trip