During the 1960s, hallucinogenic drugs were called psychedelics. This category includes LSD, peyote, mescaline, the psilocybin mushroom, DMT, DET, and MDMA. Many other chemicals and botanicals are hallucinogenic in effect, but they are relatively infrequently used. The terms "psychedelic" and "hallucinogen" convey almost opposite points of view on the drug experience, and each is likely to be used by ideologues of directly contrary opinions. "Psychedelic" contains a not-so-hidden prodrug bias: It means that the mind is "made manifest" when it is under the influence of a psychedelic drug—that we can think and see more clearly, more acutely, more deeply. The ideology underlying the "psychedelic" philosophy is (or was when the term was in vogue in the mid-1960s) that we are creatures who have been lied to and blinded by the propaganda socialized into us from infancy. No one is able to see reality "as it really is," except a tiny number of genius visionaries.

The vision and thoughts of nearly everyone are warped by the "games" imposed by a fearful and restrictive social order. The essential function that psychedelics serve, according to this view, is to strip away the impediments to a direct confrontation with reality; they allow the drug user to see things clearly, without society's lies. As Aldous Huxley exclaimed under the influence of mescaline upon witnessing the awesome "isness" of his trousers, his bookshelf, the legs of a chair: "This is how one ought to see, how things really are" . The psychedelicists claimed that far from providing an escape from reality, drugs such as mescaline and LSD offer a direct confrontation with reality, a plunge into a uniquely unadulterated world. And the term "psychedelic" captures this perspective. The ideology has to a great degree diminished in importance, but the word remains. In any case, I do not intend any prodrug bias when I use the term "psychedelic."

Almost the opposite point of view is summed up in the word "hallucinogen." Since we live in an age that thinks of itself as scientific, anything called a "hallucinogen" is something illusory—a deception, a fallacy, perhaps even the ravings of a madman, and hence something undesirable, the manifestations of a sickness calling for firm treatment. Another related term is "psychotomimetic"—having the quality of producing a state that "mimics" madness, very much like insanity in important respects. Both of these terms are obviously negatively charged and ideological in import. Actually, a true hallucination is relatively rare during the "hallucinogenic" drug experience. (Just as the mind being "made manifest," or operating most clearly, under a "psychedelic" drug is rare.) Again, when I use the term "hallucinogen" I intend no ideologically overtoned meaning. I will use the terms as if they were neutral and simply descriptive, because no completely unbiased term exists.

What are the psychedelics, or hallucinogens? Lysergic acid diethylamide, or LSD-25, or simply LSD (or "acid"—almost the only slang street term that is used routinely), is by far the best known of all psychedelics. LSD is a semisynthetic drug derived from the principal active agent in the ergot fungus, a contaminator of rye; the fungus is itself psychotoxic—in fact, an epidemic that killed thousands of people in the Middle Ages was caused by the eating of rye bread contaminated by ergot. LSD was synthesized and named by the Swiss chemist Albert Hofmann in 1938 (LSD is an abbreviation of the German term lysergsaure diethylamid—if it had been discovered by an English-speaking chemist, it would have been abbreviated LAD), but its potent psychoactive properties were not discovered until 1943, when Hofmann accidentally inhaled a minute quantity of the drug. Describing his experiences (the first LSD "trip" in history), Hofmann wrote: I had to leave my work in the laboratory and go home because I felt strangely restless and dizzy. Once there, I lay down and sank into a not unpleasant delirium  which was marked by an extreme degree of fantasy. In a sort of trance with closed  eyes... fantastic visions of extraordinary vividness accompanied by a kaleido   scopic play of intense coloration continuously swirled around me. After two   hours this condition subsided. Later, after discovering that it was the LSD that caused these reactions, and after some additional self-experimentation, Hofmann wrote: "This drug makes normal people psychotic."

LSD is taken via a swallowed capsule or tablet; at one time it was taken in the form of sugar cubes impregnated with a drop of the chemical, but this method is totally unknown today. Even as minute a quantity as 25 micrograms of LSD is psychoactive for most people. (An ordinary headache tablet contains more than 300,000 micrograms of aspirin.) The usual dose of LSD is purported to be between 200 and 500 micrograms; however, since blackmarket LSD is both contaminated (often with amphetamine) and unstandardized as to potency, very few users of street LSD can be even remotely sure of the dosages they take, in spite of their claims. An LSD "trip" customarily lasts between hve and twelve hours, although reactions, sometimes of an undesired, uncomfortable, and even frightening nature, can last for days. "Flashbacks," or recurrences of the LSD experience without taking the drug, also sometimes occur.

Mescaline ("mesc") is a naturally occurring psychedelic drug named after the Mescalero, an Apache tribe. It is in extremely infrequent use, though many naive users buy and take a chemical their dealers tell them is mescaline. (It is usually LSD, often cut with an amphetamine.) Mescaline is one of the eight or so psychoactive chemicals in the peyote cactus. Another naturally occurring psychedelic drug, psilocybin, is derived from Psilocybe mexicana, the so-called sacred or magic mushroom. Both peyote and the sacred mushroom are used in religious ceremonies by Native Americans, peyote mostly in the United States, and the sacred mushroom in Mexico. The peyote cult existed before the invasion of America by the Europeans, but it became widespread only with the destruction of much of Indian civilization. Members of the Native American Church take peyote as a sacrament—the drug represents the body of Christ—and this practice is legal in the United States.

Dimethyltriptamine, or DMT for short, and diethyltriptamine, or DET, are synthetic hallucinogens, and they deliver a powerful but extremely brief trip, sometimes lasting only fifteen minutes. For this reason they have been called the "businessman's" or "lunchtime" psychedelics. At one time, it was common to chew morning-glory seeds to bring on a hallucinogenic experience. Some genuses of morning-glory seeds contain a substance whose chemical structure is closely related to LSD's. Its psychoactive properties were known to the Aztecs, who referred to the plant as "ololiuqui." Today few young people eat morning-glory seeds, partly because the commercially sold variety began to be sprayed with a substance that induces vomiting.

There are also a number of more exotic and less frequently used hallucinogenic substances, both synthetic and naturally occurring. The mushroom Amanita muscaria, or fly agaric, has been used for centuries for its psychoactive properties by various Siberian tribes, such as the Chuckchee. It is almost unknown in America. The South American vine Banisteriopsis caapi produces a drug, usually called "yage" (pronounced "ya-hay"), that is used by some Amazonian tribes. Ingesting it produces a psychic state that could be called psychedelic or hallucinogenic. Some avant-garde literary figures, such as William Burroughs, journeyed to South America to experience the drug's effects and to write about it. In spite of its underground notoriety, I have never encountered anyone who claims to have taken yage. Another drug, bufotenine, is derived from the skin of one species of toad and seems to have some mind-altering qualities. It is almost never used in the United States. Common household nutmeg, if taken in sufficient quantities, produces an intoxication that might be called hallucinogenic. In spite of the fact that it was once used in prisons (described by Malcolm X in his autobiography), and in spite of its ready availability in the United States— which imports more than 5 million pounds yearly, mostly from Indonesia— it is not a frequently used drug. Relatively few young people are even aware of its consciousness-altering properties.

A tranquilizer that had been available on American streets since the 1960s made a resurgence in the late 1970s. It was originally called THC by drug dealers, but it was not the active ingredient in marijuana and hashish of the same name. Instead, it was a commercially manufactured animal tranquilizer known as PCP, with the chemical name of phencyclidine and the trade name of Serinyl. The Food and Drug Administration regards the drug as unsafe for human use, and it is used only to sedate and anesthetize large animals. It is now manufactured illegally and is sold as angel dust; it is often sprinkled in marijuana joints. Many observers classify this drug as a hallucinogen . This is, I believe, a mistake, as a comparison between its effects and those of LSD will quickly verify. Except for hallucinations (often horrifying with angel dust, occasionally so with LSD) and psychotic episodes (more common with angel dust than with LSD) the two drugs have nothing in common. Angel dust has none of the major effects of hallucinogens. Objectively, these drugs are simply not in the same category, although most observers do classify them together.