Can you imagine riding a bicycle on acid?

On April 19, 1943, Albert Hofmann, the Swiss father of psychedelic medicine, dropped lysergic acid diethylamide and went on a bike ride, becoming the first human to ever trip on acid. The rest is psychedelic history.

Hofmann had synthesized LSD in his lab as a medical stimulant for the respiratory and circulatory system in 1938, but at the time he didn’t know what powers it held. Revisiting his discovery five years later, he caught a glimpse of its effects when some of the drug was absorbed through his fingertips, describing the experience as “dream-like” and a “not unpleasant intoxicated-like condition.”

Intrigued, three days later — on a day that would go down in history as “Bicycle Day” — he did what any responsible scientist would do: Experiment on himself.

Taking a dose of 250 micrograms in his laboratory, thinking it was an appropriate threshold dose (we know now that he overdid it; 200 micrograms is the standard), Hofmann turned on, tuned in, and dropped out for the first time. Within an hour, his perception began to ebb and flow rapidly, and he began to freak out, convinced that his neighbor was a witch and that he was going insane. Hofmann wanted to go home.

Unfortunately, Hofmann had no access to a car because of wartime restrictions, so he had to make the journey home by bicycle. The trip was a stressful one — his vision wavered and he felt as though he were motionless — but as soon as he reached his condition’s climax, he came back from a “weird, unfamiliar world” to reassuring everyday reality.

In his notes, he went on to describe the hallucinogenic trip that would go on to inspire a countercultural revolution and, decades later, a generation of scientists looking to harness LSD’s powers to treat mental health issues:

Now, 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 stigma leftover from the 1960s remains hard to shake, but LSD has slowly been undergoing a rebrand in recent years that is much more in line with Hofmann’s original vision: Using it as a treatment for psychiatric ailments.

Just this month, scientists applied cutting-edge neuroimaging techniques to find out what exactly LSD does to the human brain, in hopes that research on the drug will regain credence in the scientific community that Hofmann himself proudly represented.

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