The Road to Eleusis by R. Gordon Wasson, Albert Hofmann, and Carl A. P. Ruck

“We, therefore, propose a new term that would be appropriate for describing states of shamanic and ecstatic possession induced by ingestion of mind-altering drugs. In Greek the word entheos means literally ‘god, (theos) within,’ and was used to describe the condition that follows when one is inspired and possessed by the god that has entered one’s body. It was applied to prophetic seizures, erotic passion and artistic creation, as well as to those religious rites in which mystical states were experienced through the ingestion of substances that were transubstantial with the deity. In combination with the Greek root gen-, which denotes the action of ‘becoming,’ this word results in the term that we are proposing: entheogen. Our word sits easily on the tongue and seems quite natural in English. We could speak of entheogens or, in adjectival form, of entheogenic plants or substances. In a strict sense, only those vision-producing drugs that can be shown to have figured in shamanic or religious rites would be designed entheogens, but in a looser sense, the term could also be applied to other drugs, both natural and artificial, that induce alterations of consciousness similar to those documented for ritual ingestion of traditional entheogens.”