LSD is an unlikely subject for a 100th birthday party. Yet the Swiss chemist who discovered the mind-altering drug and was its first human guinea pig is celebrating his centenary Wednesday — in good health and with plans to attend an international seminar on the hallucinogenic.

"I had wonderful visions," Albert Hofmann said, recalling his first accidental consumption of the drug.

"I sat down at home on the divan and started to dream," he told the Swiss television network SF DRS. "What I was thinking appeared in colors and in pictures. It lasted for a couple of hours and then it disappeared."

Hofmann, who also had bad experiences with the drug, continues to insist it should be legalized for medical treatment, particularly in psychiatric research. But LSD's reputation has been as turbulent as some acid trips.

The drug earned a bad reputation amid fatalities associated with hallucinations and reports of "flashbacks" — the recurrence of hallucinations when not taking the drug.

LSD inspired the 1960s hippy generation and was immortalized in the Beatles' hit "Lucy in the Sky with Diamonds," although the band denied any connection. But it was also known as Like Swift Dead.

For decades after LSD was banned in the late 1960s, Hofmann defended his invention.

"I produced the substance as a medicine," he said. "It's not my fault if people abused it."

The chemist — who still takes nearly daily walks in the picturesque village where he lives in the Jura mountains with his wife of 70 years, Anita — discovered lysergic acid diethylamide-25 in 1938 while studying the medicinal uses of a fungus found on wheat and other grains at the Sandoz pharmaceuticals firm, now part of Novartis.

The company declined to comment for this story.

Hofmann was the first person to test the drug when a tiny amount of the substance seeped on to his finger during a repeat of the laboratory experiment in April 1943.

"Everything I saw was distorted, as in a warped mirror," he wrote of the experience, noting his surprise that LSD was able to produce "such a far-reaching, powerful, inebriated condition without leaving a hangover."

The chemist experimented with a larger dose three days later, but the result this time was a "horror" trip, he wrote. His surroundings turned into threatening images. A neighbor was transformed into a wicked witch.

"I was filled with an overwhelming fear that I would go crazy. I was transported to a different world, a different time," he wrote.

Hofmann and his scientific colleagues hoped LSD would make an important contribution to psychiatric research. The drug exaggerated inner problems and conflicts, and they hoped it might be used to recognize and treat mental illnesses like schizophrenia.

The drug was popularized by Timothy Leary, the one-time Harvard lecturer known as the "high priest of LSD," whose "turn on, tune in, drop out" advice to students in the 1960s glamorized the hallucinogen. The film star Cary Grant and numerous rock musicians extolled its virtues in achieving true self-discovery and enlightenment.

But away from the psychedelic trips and flower children, stories emerged of people going on murder sprees or jumping out of windows while hallucinating. Heavy users suffered permanent psychological damage.

The United States banned LSD in 1966 and other countries followed suit.

Hofmann maintains that was unfair, arguing the drug was not addictive. He has repeatedly said the ban should be lifted so LSD can be used in medical research, and he took the drug himself — purportedly on an occasional basis and out of scientific interest — for several decades.

But he added a note of caution.

"The history of LSD to date amply demonstrates the catastrophic consequences that can ensue when its profound effect is misjudged and the substance is mistaken for a pleasure drug," he wrote.