Exactly 71 years ago, April 19, 1943, Albert Hofmann, a chemist for Sandoz, in Basel, Switzerland, ingested a minute amount—just 250 micrograms--of a compound derived from the ergot fungus. He soon felt so disoriented that he rode his bicycle home, where he experienced all the heavenly and hellish effects of lysergic acid diethylamide.

Beside this artistic evocation of psychedelic visions, a display of “scientific” posters—with titles like “Psychoneurophysiology of Personalized Regression and Experiential Imaginary Therapy”--seemed parodically dry. The meeting’s schizoid character was reflected in its speakers, too. One group sported hippy-ish threads and extolled altered states in subjective, even poetic language. The other wore jackets and ties and employed clinical, objective rhetoric.

The meeting's guest of honor was a stooped, white-haired man with fierce, Churchillian mien: Albert Hofmann. His contributions to psychedelic chemistry extended beyond LSD. In the 1950s, he analyzed Psilocybe cubensis, a “magic mushroom” consumed by Indians in Mexico, and deduced that its primary active ingredient is psilocybin. Hofmann's research inspired other scientists around the world to investigate LSD, psilocybin and similar compounds, which psychiatrist Humphry Osmond dubbed psychedelic, based on the Greek words for “mind-revealing.”

At 93, Hofmann still avidly followed the field he helped create. One day we spoke during the lunch break, and Hofmann, in halting, heavily accented English, vigorously defended LSD, which he called his “problem child." He blamed Harvard-psychologist-turned-counterculture-guru Timothy Leary for giving LSD such a bad reputation.

“I had this discussion with him," Hofmann told me. "I said, ‘Oh, you should not tell everybody, even the children, “Take LSD! Take LSD!”'" LSD “can hurt you, it can disturb you," Hofmann said, "it can make you crazy.” But properly used, psychedelics stimulate the “inborn faculty of visionary experience” that we all possess as children but lose as we mature.

Hofmann recalled a psilocybin trip during which he ended up in a ghost town deep inside the earth. “Nobody was there. I had the feeling of absolute loneliness, absolute loneliness. A terrible feeling!” When he emerged from this nightmare and found himself with friends again, he felt ecstatic. “I had feeling of being reborn! To see now again! And see what wonderful life we have here!” The gruff old man stared above my head, his eyes gleaming, as if born again this very moment.

In his writings, Hofmann occasionally divulged misgivings about having brought LSD and psilocybin into the world. In a letter in 1961, he compared his discoveries to nuclear fission; just as fission threatens our fundamental physical integrity, he said, so do psychedelics “attack the spiritual center of the personality, the self.” Psychedelics, Hofmann fretted, might “represent a forbidden transgression of limits.”

On the last day of the conference, I had several hours to kill before dinner, which I planned to spend with two psychiatrists, American and Russian. As people filed out of the convention hall, I idly checked out the tables in the lobby and realized to my surprise that one was was covered with hallucinogens: a potted peyote cactus festooned with wrinkled buttons; beige-capped mushrooms, identified as Psilocybe cubensis, sprouting in an aquarium; and a bundle of black leaves labeled Salvia divinorum.

Are these for sale? I asked a lank, blond youth manning the table. Yes, he replied with a German accent, and an implied “Duh.”

Inspiration struck: I should supplement my objective reporting on this meeting with an actual trip! I asked the vendor to recommend something, not too strong or long-lasting. He suggested mushrooms. The Psilocybe cubensis in the aquarium were not for sale, but he could sell me a fungus that produced a milder high. He told me the mushroom’s scientific name, which sounded to me like Psilocybe simulata.

Aha, I cleverly thought, this substance probably simulates the effects of real psilocybin but isn’t as potent. Perfect. I bought an envelope containing four grams of the stuff--the recommended dose--and returned to my hotel room.

Just to be safe, I ingested only half of the brown and yellow fragments in the envelope. Within 15 minutes the walls of my room were seething, as were my thoughts and emotions. This was definitely not simulated psilocybin but the real thing. I briefly closed my eyes and found myself immersed in a boiling vat of brilliant dyes, bubbling furiously up at me.

Opening my eyes, I recalled the hallucination hypothesis of mathematical biologist Jack Cowan. Psychedelics, he told me, stimulate neurons in the visual cortex dedicated to detecting edges of objects. Excessive firing of these specialized neurons generates the spirals, lattices, tunnels, checkerboards and convective swirls familiar to psychedelic users.

Not even this reductionist recollection could stem my mounting panic. The walls of my room trembled like membranes, which were about to burst and let the clear light of the void flood over me. I wasn’t ready for a confrontation with ultimate reality. I berated myself for taking the mushrooms so casually. This is not a game, I thought. This is not a game.

I stumbled into the bathroom and stuck my fingers down my throat in an attempt to vomit up the mushrooms--in vain. I debated skipping my dinner date with the two psychiatrists but concluded that I had nothing to fear. The psychiatrists had positive views of psychedelics, or they wouldn't be at this conference.

I ventured out of my room and onto the boulevard in front of my hotel. I found myself walking behind an odd quartet, three humans and a dog. If I had not seen other pedestrians gawking at them, I might have thought they were hallucinations. In the center was a man with short-cropped blond hair and cruel, chiseled features, well over six feet tall, clad in black leather. He strode shoulder to shoulder with an equally tall, blond, hollow-cheeked woman, also sheathed in black leather, walking a black, pony-sized Doberman wearing a spiked collar. Skipping beside this Aryan god, goddess and beast was a tiny person, scarcely taller than the dog, wearing a belled jester’s cap. Male or female? Child or midget? I could not tell.

I skulked behind this foursome for a block or so. Then, fearing they might think I was stalking them, I veered to the opposite side of the boulevard, past a pack of feral children swarming around a shop window. A block later, I glanced inside the glass front doors of a hotel and saw a half dozen people just inside, chatting. Albert Hofmann stood in the middle of the group, facing me.

I had an eerie moment as my psilocybin-addled brain absorbed the image of this psychedelic Prometheus, this external personification of my subjective, inner state. Then I panicked. What if he spots me and calls me over! What will I do? I will be tongue-tied and make a fool of myself! Albert Hofmann will know I’m tripping! I averted my gaze and scurried onward.

The convention-center lobby, my rendezvous point, was dimly lit and seemed deserted. Then someone called my name, and two men strode out of the shadows. The man who had addressed me was John Halpern, the Harvard psychiatrist with whom I had arranged this dinner date. Halpern introduced me to Evgeny Krupitsky, who headed a substance-abuse clinic in Saint Petersburg, Russia. Krupitsky had a thatch of salt and pepper hair, a Groucho Marx moustache and a perplexed, kindly expression.

Not yet thirty, Halpern was prematurely balding, but his face and demeanor were otherwise boyish. He radiated jittery, impatient energy, and he spoke extremely rapidly. He seemed to be a different species than Krupitsky and I, a spider monkey to our slow lorises. Rubbing his hands together briskly, Halpern told us that he had made reservations at Basel's finest restaurant.

There’s something I should tell you, I stammered. The words seemed to come from someone else, a dummy standing beside me.

What’s the problem? Halpern replied, scrutinizing me.

I, uh, took something, I heard myself say. A drug.

What’d you take? Halpern asked. When I hesitated, he added, incredulously, You don’t know what you took!? He barraged me with questions, to which I haltingly responded. Halpern was familiar with the vendor who had sold me my intoxicant. He rapidly deduced that I had purchased Psilocybe semilanceata, also known as liberty caps, indigenous to the Pacific Northwest and other cool, moist climes. Sometimes called the champagne of psychedelics. I had eaten the mushrooms about, what, ninety minutes ago? I should be peaking about now, seeing some visual effects, feeling pretty high. I nodded, immensely relieved to have my condition so expertly categorized.

Did I think I could handle dinner, Halpern asked, or did I want to bow out?

If you and Evgeny can put up with me, I answered, I wouldn’t mind joining you.

Great! Halpern said.

I blurted out that I felt like an idiot for having taken these mushrooms in such a casual manner. I knew how dangerous drugs could be; you could end up in a mental hospital.

Smiling, Halpern reminded me that he and Evgeny commit people to mental hospitals for a living. He was sure Evgeny would agree that psychedelics rarely cause genuine psychosis—the kind that requires hospitalization--in otherwise stable people; there is almost always a history of prior mental illness. That is not to say psychedelics are risk-free, particularly if you’re a neurotic teenager. As Halpern spoke, Krupitsky nodded at me reassuringly.

Outside the convention hall, Halpern hailed a cab and jumped in the front seat; Krupitsky and I sat in the back. We seemed to drive forever, arcing over stone bridges, sailing across squares, creeping down narrow winding streets. Buildings, cars, trees, signs, everything looked streamlined, gorgeous, opulent, bathed in glycerin, and aroused in me a tactile, feathery pleasure.

As we rounded a cobblestoned corner, a silver Porsche glided noiselessly past us, like a stingray cruising an ocean floor. The restaurant bordered a canal, its surface satiny and textured as a raven’s wing. The restaurant’s windows were beveled, like huge diamonds, and ringed by Christmas lights. The restaurant was equally lovely within. The candles, crystal, silverware, flowers, lacquered wood all glowed rosily, as did the young blond woman serving us.

After ordering for Krupitsky and me, Halpern served as conductor of our conversation. At Halpern’s urging, Krupitsky told me about his investigation of ketamine as a treatment for alcoholism. Ketamine is a general anesthetic—used more often in veterinary than human medicine--that when injected at sub-anesthetic doses triggers an extremely disorienting hallucinogenic episode lasting an hour or so.

Since the early 1980s, Krupitsky has been successfully treating alcoholics with ketamine supplemented by individual and group psychotherapy. He was careful to qualify his results. He noted that those who submit to ketamine therapy after being forewarned about its harrowing aspects might be more highly motivated to stop drinking than run-of-the-mill alcoholics.

I vaguely recalled that ketamine had been a favorite drug of John Lilly, pioneer of dolphin-language studies, inventor of sensory-isolation tanks, and all-round polymath. He was the role model for the brilliant-but-unstable researcher played by John Hurt in the movie Altered States. Late in his career, Lilly became obsessed with ketamine, injecting himself for days on end. He claimed that during these binges he made contact with solid-state, extra-dimensional aliens distressed by humanity’s treatment of dolphins and other animals.

Krupitsky assured me that the patients in his studies take ketamine only a few times, at most, under safe, supervised conditions. The ketamine experience can be ego-shattering, but that is the point. Therapists hope to get alcoholics to feel revulsion toward their former way of life. One trick the therapists employ is to make ketamine-intoxicated patients sniff a bottle of booze; the patients often feel a disgust that persists long after the ketamine’s effects have faded. Krupitsky had been invited by researchers at Yale to collaborate on a similar treatment program.

Telling me all this, Krupitsky was soothingly phlegmatic. His English was a bit shaky, though, and he showed no irritation when Halpern broke in to clarify, annotate or digress.

Halpern told me about his investigation of the effects of peyote on members of the Native American Church. According to Halpern’s preliminary results, church members showed no ill psychological or physiological effects from peyote; in fact, they were in general healthier and happier—and less prone to alcoholism—than non-church members. Halpern was careful to point out that these benefits could derive from the social fellowship provided by church membership.

Halpern periodically asked me how I was doing, and I kept saying, Fine. He advised me to close my eyes for fifteen seconds to test my “visuals.” I closed my eyes for few seconds and--dizzied by the riotous polychromatic swirling—opened them again. I’m fine, I reiterated.

Halpern launched into a paean to psilocybin mushrooms. Here I was, quite intoxicated, and yet I could still handle myself in a highly structured social setting with no obvious signs of disorientation.

Yes, I crowed, I love my job! Halpern and Krupitsky averred that they loved their jobs, too. I raised my mug of beer, Halpern his goblet of wine and Krupitsky his tumbler of water. Clinking our glasses together, we toasted our good fortune.

Of course, psychedelics can be employed for insidious ends, Halpern reminded us. Beginning in the early 1950’s, he recalled, the Central Intelligence Agency created top-secret programs such as Bluebird, Artichoke and MK-Ultra to investigate the potential of LSD and other drugs as truth serums and brainwashing agents.

The CIA paid psychiatrists to test LSD on prisoners and mental patients. Ewen Cameron, former head of the American Psychiatric Association, tried to “re-program” patients by piping tape-recorded exhortations into their rooms after they had been rendered malleable by barbituates, LSD and electroshock therapy. The U.S. Army gave LSD to soldiers engaged in field exercises, too. Halpern had seen film footage of the exercises, in which the soldiers staggered about comically.

In the 1960s and 1970s, the Army stockpiled tens of thousands of canisters of an extremely potent hallucinogen, 3-Quinuclidinyl benzoate, or BZ. BZ, if wafted in aerosol form over enemy troops, could turn them into gibbering idiots for up to 80 hours. BZ was never deployed, apparently because American military commanders feared the unpredictability of its effects; killing the enemy with bullets and bombs was more reliable.

Halpern occasionally interrupted this litany to ask me if I found it disturbing. Not at all, I replied, I find it fascinating. And that was true. But I also was vaguely convinced that this was my much-deserved penance for having eaten mushrooms so blithely this evening. I was being reminded that the world does not exist merely for my aesthetic delectation.

Psychedelics, an enthusiast once assured me, reveal existence to be a divine dance, a game, which we should play joyfully. If only things were that simple. Yes, the world is miraculous, and heartbreakingly beautiful, but it is ugly, too, marred by injustice, cruelty, greed, violence and terrible suffering. This is what theologians call the problem of evil. There are bad people out there, including some who have used psychedelics for evil ends. Albert Hofmann acknowledged as much. The same drug that awakens us can enslave us or drive us mad.

I didn’t reveal these dark thoughts to Halpern or Krupitsky. As they kept talking, I just nodded along, thinking, This is not a game. This is not a game.

Self-plagiarism alert: I've described my 1999 trip to Basel in Rational Mysticism and elsewhere.