Vulgar Substitute

Narcotics are only a vulgar substitute for "pure" trance. We have already had occasion to note this fact among several Siberian peoples; the use of intoxicants (alcohol, tobacco, etc.) is a recent innovation and points to a decadence in shamanic technique.  Narcotic intoxication is called on to provide an imitation of a state that the shaman is no longer capable of attaining otherwise. 

Eliade, Mircea.  
Shamanism: Archaic Techniques of Ecstasy (1964).
New York: Pantheon.

On the contrary...^> (Terence McKenna)