right|thumb|LSD [[blotter paper]]
The psychedelic drug (or entheogen) lysergic acid diethylamide (LSD) was first synthesized on November 16, 1938, by the Swiss chemist Albert Hofmann in the Sandoz laboratories in Basel, Switzerland. It was not until five years later on April 16, 1943, that the psychedelic properties were found.
Discovery
Albert Hofmann, born in Switzerland, joined the pharmaceutical-chemical department of Sandoz Laboratories, located in Basel, as a co-worker with professor Arthur Stoll, founder and director of the pharmaceutical department. He began studying the medicinal plant squill and the fungus ergot as part of a program to purify and synthesize active constituents for use as pharmaceuticals. His main contribution was to elucidate the chemical structure of the common nucleus of Scilla glycosides (an active principle of Mediterranean squill). He described what he felt as being:
Bicycle Day
On April 19, 1943, Hofmann ingested 0.25 milligrams (250 micrograms) of the substance, which he estimated to be a small dose, but is actually about 10 times the minimum amount that produces a psychedelic effect. Between one and two hours later, Hofmann experienced slow and gradual changes in his perception. He asked his laboratory assistant to escort him home. As was customary in Basel, they made the journey by bicycle. On the way, Hofmann's condition rapidly deteriorated as he struggled with feelings of anxiety, alternating in his beliefs that the next-door neighbor was a malevolent witch, that he was going insane, and that the LSD had poisoned him. When the house doctor arrived, however, he could detect no physical abnormalities, save for a pair of widely dilated pupils. Hofmann was reassured, and soon his terror began to give way to a sense of good fortune and enjoyment, as he later wrote:
The events of this first LSD trip, now known as "Bicycle Day", after the bicycle ride home, proved to Hofmann that he had indeed made a significant discovery: a psychoactive substance with extraordinary potency, capable of causing significant shifts of consciousness in incredibly low doses. (The term trip was first coined by US Army scientists during the 1950s when they were experimenting with LSD.) Hofmann foresaw the drug as a powerful psychiatric tool; because of its intense and introspective nature, he could not imagine anyone using it recreationally.
Bicycle Day is an informal celebration on April 19th of the anniversary of this first LSD trip, and the psychedelic revolution in general. It is sometimes celebrated by riding a bike on psychedelics and/or in a parade, and often with psychedelic-themed festivities. The celebration of Bicycle Day originated in DeKalb, Illinois, in 1985, when Thomas B. Roberts, then a professor at Northern Illinois University, invented the name "Bicycle Day"