The abbreviation LSD, commonly used, refers to the molecule LSD-25, or lysergic acid diethylamide. This LSD was first synthesized in the mid-20th century and is known for its effect in producing changes in sensation, perception, and consciousness in humans. This effect has been alternately described as psycholytic, psychedelic, psychomimetic, hallucinogenic, or entheogenic, depending on the age, the describer, and the framework in which they are analyzing it.

In structure, affective mechanism, effects, and use, LSD is similar in some degree to psilocyn, psilocybin, and mescaline, although it is different from these substances and most other pharmaceuticals of all kinds in that it produces effects at very low dosages, its influence noticeable in humans at the high two-digit microgram range. LSD is used for psychiatric, religious, and recreational purposes, though it is best known for the latter, and while most experts who have studied it believe it to have no immediate or long-term negative physical effects, fears of psychological damage and social and political concerns have lead to the criminalization of its manufacture, sale, possession, and/or consumption in many areas worldwide.

LSD was originally produced in 1938 by the chemist Albert Hofmann at the German company Sandoz Pharmaceuticals, in the course of a study of alkaloids found in the grain fungus ergot. Ergot had long been known as a poison which induced symptoms, collectively known as ergotism or "Saint Anthony's Fire", which included hallucinations and severely altered mental states. Ergot had also, however, proven useful as a source of folk medicine for use in childbirth, and in the 1930s chemists began to learn about ergot alkaloid structures (all shared a core of lysergic acid) and produce ergot derivatives, principally ergotamine, which were found to have marketable medical applications.

Lysergic acid diethylamide was Hofmann's 25th lysergic acid derivative, and the rest of its anglophonically unintuitive abbreviation is accounted for by the fact that it was given the German appellation of "lyserg saure diathylamid". On the basis of similarity to other diethylamides, LSD was expected to have analeptic (respiratory and circulatory stimulant) properties. Animal testing, however, did not indicate much promise as a pharmaceutical product, though the test subjects were noted to show some signs of restlessness and agitation.

The effects LSD is now principally known for were not discovered until 1943, when Hofmann, believing it would yet show some usefulness, synthesized another batch and in so doing apparently came into contact with the substance, which was absorbed transdermally, through the skin. Hofmann's synthesis was "interrupted by unusual sensations", and he returned home, reporting restlessness, dizziness, and the experience of seeing a dreamlike play of pictures, shapes, and colors with his eyes closed.

Three days later, to confirm his suspicion that this experience was a product of LSD, he intentionally ingested a quarter of a milligram (an amount roughly equal to two to four modern-day "hits" of the drug), and experienced delirium, strange and threatening changes in the visual appearance of physical objects and in his perception of time, disassociation, and a sense of his impending death, part of what would now be considered a "bad trip", surely aggravated by his complete unawareness of any precedent for this effect. A doctor his assistant summoned reported no apparent physical effects, however, and the symptoms eventually faded to a pleasant synaesthesia before ultimately disappearing and leaving behind no ill effects.

Hofmann's experiences proved replicable, and further study into the effects of LSD and related compounds was conducted. The possible market for such a drug was not immediately apparent, but it was soon seized upon by psychiatrists, who used it in attempts to understand the viewpoint of the schizophrenic or otherwise mentally atypical patients they worked with. Some of these professionals later found it more useful when administered to patients in conjunction with talk therapy, a strategy many therapists found useful in reducing inhibitions, producing revelations and breakthroughs in self-awareness, and in assisting patients in addressing traumatic or repressed memories and events from their past. Sandoz was more than happy to service this market, distributing LSD under the brand name Delysid.

LSD was also early on seized on for its possible religious significance, encouraged by contemporary interest spurred by Aldous Huxley, R. Gordon Wasson, and others in the role of mind-affecting fungi, peyote, and similar substances in the shamanic religions of ancient Europe, India, and the native peoples of America. The use of LSD in a religious context was not limited to animistic traditions, however. Al Hubbard, a maritime entrepreneur with an unusual background, strongly promoted its use in the context of Catholicism, sparking some interest in the church in western Canada, while Walter Pahnke's "Good Friday Experiment" indicated the usefulness of the similar psychedelic psilocybin in producing transcendent religious experiences among a group of Harvard Divinity School students.

The United States government also took interest in LSD, investigating its effects and possible uses, most famously as a possible truth serum and mind control agent in the MKULTRA tests, a purpose for which it was ultimately deemed unsuitable. Though it made use of such unscrupulous methods such as administration to subjects without informed consent, including subjects who did not even know they were part of a test at all, the government also conducted standard experiments for which it recruited volunteers from academia. Between these tests, similar experiments carried out by private research institutes, the use of LSD in psychiatric therapy, and later self-administration outside of an institutional context, a significant amount of the United States intelligentsia first encountered LSD, either through direct experience or secondhand accounts, in the 1950s and 1960s.

Though growing awareness of the drug by way of dissemination downwards from the intellectual class and upwards from the popular media accounts of LSD research meant that its introduction into the mainstream culture was more or less inevitable, this process was immeasurably hastened by Harvard psychology professor Timothy Leary. After encountering psilocybin in Mexico in 1960, Leary began to work with LSD, for which he became a fierce evangelist, first privately and soon publicly, continuing after his dismissal from Harvard in 1963. Simultaneously, the demand for LSD in quantities greater than official sources were capable of — or willing to — supply inspired independent producers, most famously Owsley Stanley, to manufacture their own LSD, motivated by profit or philosophy.

Even this, by itself, might not have prevented the successful integration of LSD into western culture. But, in one of those coincidences of history, these developments occurred simultaneously with the emergence in America of a strong youth and dissident subculture, itself the product of several cultural trends converging - reaction against the Cold War in general and the Vietnam War in particular, high tensions over civil rights and the role of women and minorities in America, uneasiness originating in the further shift from an agricultural to an industrial economy and the development of consumerism, and the latest incidence of the recurrent utopianism, frequently associated with strong but nontraditional spiritualism, free love, communal living, socialism, and withdrawal from the mainstream culture, that has periodically arisen every few decades in America since at least as far back as the early 19th century. Many members of this subculture, which tend to get labeled with the catchall appellation of "hippies", embraced LSD for spiritual and recreational purposes, integrating its use as an important, if not fundamental, aspect of their identity and lifestyle.

The dominant culture, left fairly unsettled by the aforementioned trends itself and rendered severely apprehensive or outright fearful about this subculture, found in LSD at least one thing it could take direct action against, and prohibited it at first the state, and then the national level in the mid-1960s. In fairness, it should be noted many citizens were truly fearful of yet unknown and possibly damaging long-term effects of LSD use, though these concerns are generally thought to have been exaggerated by sensationalistic press and government treatment more concerned with public order. Other governments, urged on by the United States and fearful that it would contribute to similar conditions of domestic unrest, followed suit.

Despite its prohibition, LSD proved rather popular as a recreational drug throughout the 1960s and 1970s. Since then its use has by no means disappeared, though it has decreased and become less prominent in response to long-term cyclical trends in drug use and the introduction of new drugs like Ecstasy (MDMA). Ecstasy, of course, after proving useful in psychiatry merged with youth subcultures in 1980s England in a manner quite similar to LSD's American experience. The "serious" work of studying LSD and its uses in religious and psychiatric contexts has to a large part been collateral damage, facing significant government-imposed barriers, but researchers have recently made some headway in this regard. Many speculators hope that with the passage of time creating a distance from the tensions surrounding its original introduction into the general society and a growing willingness among western nations to reassess their policies on recreational drug use, LSD may yet be integrated into mainstream culture.


References:
Albert Hofmann - LSD - My Problem Child
Jay Stevens - Storming Heaven: LSD and the American Dream
Martin A. Lee & Bruce Shlain - Acid Dreams: The Complete Social History of LSD: The CIA, the Sixties, and Beyond
Some information probably originally from Lycaeum (www.lycaeum.org), Erowid (www.erowid.org), and the Multidisciplinary Association for Psychedelic Studies, it's been a while.