Certain plants have long been known to humans as having psychoactive effects—they produce changes in a person's thoughts, sensations, and behavior. Drugs made from such plants played important roles in many societies before the modern age. People viewed these substances as sources of the sacred and spiritual realms. These plants were generally used in community rituals meant to improve health and to strengthen responsible behavior by members of the community. They were not used as drugs of abuse. Plants such as the psilocybin mushrooms, iboga, ayahuasca, datura, betel, and kava served four basic purposes: (1) to help a person achieve an experience of the sacred; (2) to help people adjust to changes in their culture; (3) to help people feel uninhibited and at ease in social situations; and (4) to treat sickness and in some cases to treat people who abused other drugs.

Mushrooms containing...