The word "psychedelic" entered the English language in 1947, courtesy of British psychologist Humphrey Osmond. In a paper he was presenting at a conference of the New York Academy of Sciences, Osmond described his own experiences with mind-altering chemicals such as LSD and mescaline. Dissatisfied with the judgmental terms that his profession typically used to describe such drugs, Osmond came up with "psychedelic" as a more neutral descriptor, and the name stuck.

Psychedelic drugs remained in the cultural background, the sole province of discreet, professional, scientific research, until 1963. That year, it became widely known that two Harvard psychology professors, Timothy Leary and Richard Alpert, were giving controlled doses of LSD to graduate student volunteer subjects. Leary and Alpert were engaged in legitimate research, and the LSD (short for lysergic acid diethylamide) had been obtained legally and with government permission. However, Harvard deemed the project irresponsible and fired both men...