And this was all before acid met the counterculture on Haight Street in the 1960s.

But meet they did, and it was love at first sight. Dr. Hofmann’s child was no hustler from a shotgun lab in Tijuana, after all, but a bourgeois revolutionary, born into establishment medicine and able to travel the world and enter societies from the top down, through their most hallowed institutions.

The English novelist Aldous Huxley, who struck up a friendship with Dr. Hofmann, was one of the first prominent proponents of LSD use for personal transformation. Timothy Leary, LSD’s pied piper, was a Harvard professor whose public raptures over the drug were a strong cocktail of mystical and scientific jargon. Ken Kesey, founder of the protoraves known as acid tests, was at age 30 already an acclaimed novelist, author of “One Flew Over the Cuckoo’s Nest.” He likened taking acid to “putting a tuning fork on your whole body.”

Not that acid was a hard sell to young people in the early 1960s, at least to those who longed not only to shake free of mainstream suburban-corporate culture but also to transform it, and themselves. They weren’t looking for an angry fix but something far grander. “To put matters bluntly: the hippies were an attempt to push evolution, to jump the species toward a higher integration,” wrote Jay Stevens in his 1987 book, “Storming Heaven: LSD and the American Dream.”

A joint is not going to get you there.

Nor, in the end, did LSD. By 1966 a raft of toxic knockoffs were on the street, and the authorities recognized that, whatever its upside, acid had become part of a self-devouring drug culture that exposed many users to a poisonous menu of illicit drugs. The government outlawed distribution of LSD, and research into its effects soon ground to a near halt. Where some saw a long-overdue crackdown on abuse, others saw an overreaction.

“Once the drug illegalization crowd gets hold of it, that’s that,” said Alexander Shulgin, a former Dow chemist who discovered the effects of MDMA, or ecstasy, which has also been made a controlled substance. “People start talking about protecting little children, and worrying about whether someone’s going to jump out the window, and meanwhile we have these substances  MDMA and LSD  that may be of tremendous value in psychotherapy and couldn’t be explored.”

They can now; several trials testing psychedelics are in the works, thanks in part to the steady example set by Dr. Hofmann. “I think people in this country, when they see a patient in pain, will not deny that person a medication just because the drug has abuse potential,” said Dr. John Halpern, a Harvard psychiatrist who is testing the effect of MDMA-assisted psychotherapy in late-stage cancer patients. “LSD is always going to be a touchy subject but I think it’s kind of fallen back to earth.”

The trip is over, the hangover gone, and the prodigal child arrived home, just in time to say goodbye.