It's possible to see the whole human growth movement of the 1970s as a wish to continue the inward quest without having to put yourself on the line in the way you had to when you took 250 gamma of LSD. And I think all these other methods are efficacious, but I think it's the sheer power of the hallucinogens that puts people off.
Terence McKennaApparently, in the Avesta classical period no one would have dreamed of having a spiritual experience without resort to drugs.
Terence McKennaThat's the core puzzling experience, when you meet the Other organized as a speaking mind.
Terence McKenna