Although the year 2012 and the Mayan Calendar are now firmly connected in the popular imagination, we will see that, in fact, the ideathat the eschaton will arrive in 2012 was originally based not on the Mayan Calendar but on a speculative macrohistory derived by Terence McKenna from the I Ching and inspired by a psychedelic revelation inthe Amazon forest. By studying the historical origins of the ‘2012 phenomenon’, we discover not only a neglected key figure in the develop-ment of alternative spirituality since the 1970s, but are also alerted to a no less neglected dimension of that development as a whole: the importance, in what is broadly referred to as the ‘New Age movement’, of psychoactive substances as catalysts of new spiritual revelations.