April 19, 1943, Hofmann performed a self-experiment to determine the true effects of LSD, intentionally ingesting 0.25 milligrams (250 micrograms) of the substance, an amount he predicted to be a threshold dose (an actual threshold dose is 20 micrograms). Less than an hour later, Hofmann experienced sudden and intense changes in perception. He asked his laboratory assistant to escort him home and, as use of motor vehicles was prohibited because of wartime restrictions, they had to make the journey on a 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 incredibly 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…
“… little by little I could begin to enjoy the unprecedented colors and plays of shapes that persisted behind my closed eyes. Kaleidoscopic, fantastic images surged in on me, alternating, variegated, opening and then closing themselves in circles and spirals, exploding in colored fountains, rearranging and hybridizing themselves in constant flux …”
The events of the 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. Hofmann foresaw the drug as a powerful psychiatric tool; because of its intense and introspective nature, he couldn’t imagine anyone using it recreationally. Bicycle day is increasingly observed in psychedelic communities as a day to celebrate the discovery of LSD.
The celebration of Bicycle Day originated in DeKalb, IL., in 1985, when Thomas B. Roberts, then a Professor at Northern Illinois University, invented the name “Bicycle Day” founded the first Bicycle Day celebration at his home. Several years later, he sent an announcement made by one of his students to friends and Internet lists, thus propagating the idea and the celebration. His original intent was to commemorate Hofmann’s original, accidental exposure on April 16th, but that date fell midweek and was not a good time for the party, so he chose the 19th to honor Hofmann’s first intentional exposure.