The ritual and medical use of narcotic drugs such as opium, or hashisch dates back several thousand years. The same applies to hallucinogens such as peyotl or hallucinogens, except that their discovery by the West was much later. Several hundred species of plants are estimated to have hallucinogenic properties spread throughout the globe. But it is in Latin America, and especially in Mexico that we meet the greatest number of people. We will examine the history of two of them, the most important: peyotl and Psilocybe fungus. They have played an important but unknown role in the history of literature and arts, as well as in the history of medicine, until now.