The notion that hallucinogenic drugs played a significant part in the development of religion has been extensively discussed, particularly since the middle of the twentieth century. Various ideas of this type have been collected into what has become known as the entheogen theory. The word entheogen is a neologism coined in 1979 by a group of ethnobotanists (those that study the relationship between people and plants). The literal meaning of entheogen is “that which causes God to be within an individual” and might be considered as a more accurate and academic term for popular terms such as hallucinogen or psychedelic drug. By the term entheogen we understand the use of psychoactive substances for religious or spiritual reasons rather than for purely recreational purposes.