Albert Hofmann was conducting research at the Sandoz Laboratories in Basel, Switzerland, focusing on ergot alkaloids when he first synthesized lysergic acid diethylamide, or LSD, in 1938. Following laboratory tests, Hofmann discovered the compound's psychoactive effects accidentally on April 16, 1943, when a small amount absorbed into his skin led to unusual sensations and perceptions. Intrigued by the effects, Hofmann decided to conduct a more controlled experiment by intentionally dosing himself with 250 micrograms of LSD three days later.

After taking the dose, Hofmann began to feel the compound's effects while cycling home. He experienced heightened sensory awareness, color vibrancy, and perceptual distortions as he pedaled through the streets. His bicycle ride became a whimsical adventure filled with hallucinations, which he later lovingly termed “Bicycle Day.” The experience not only influenced Hofmann personally but also laid the groundwork for LSD's introduction into popular culture and psychology.

The event captured the imagination of the wider community and marked the beginning of LSD as a substance of interest for various fields, including psychiatry, psychotherapy, and recreational use. Over the coming decades, it would be both celebrated for its potential and criticized for its misuse and associations with counterculture movements.