It was the fall of 2012, and Sarlo knew his quest seemed absurd. After all, his father had been dead for decades, and he had no connection to this region of rainforests and beaches and its indigenous peoples. As the financier watched a shaman prepare a ceremonial cup of bitter brown ayahuasca, he couldn't believe that he'd agreed to swallow this nauseating psychedelic brew for a second time.

Deep in the Mexican jungle, in a village so remote it's only accessible by boat, 74-year-old venture capitalist George Sarlo waited to meet his father.

Not far away, his own 1920s mansion also overlooks the bridge, taking in the entire 180-degree sweep of the bay. Salesforce billionaire Marc Benioff lives in the neighborhood; across the street is Robin Williams's former home.

His philanthropy has supported a humanitarian award in his name at the International Rescue Committee, two endowed chairs at the University of California, San Francisco, and funded Immigrant Point Lookout, a gorgeous spot in a beautiful public park: San Francisco's Presidio, near the Golden Gate Bridge.

"There are opportunities where relatively small amounts of money and energy can have a tremendous impact. So that's what I'm looking for."—George Sarlo

Though consuming ayahuasca in a Mexican jungle might complicate the picture, in many ways George Sarlo personifies the American Dream. In fact, his rags-to-riches refugee story is included as one of less than three-dozen examples in a new online exhibit on becoming an American at the Smithsonian Institution's National Museum of American History in Washington. As co-founder of Walden Venture Capital, which he helped start in 1974 and which currently manages some $107 million in funds, he has overseen the investment of billions of dollars.

A shaman had also assured Sarlo that the veil between worlds would be thinner at this time, during Mexico's Day of the Dead, which runs from Halloween through November 2. Since he had survived the past night's ordeal—with all of its vomiting and visions of sepia-colored soldiers—he figured he had little to lose by trying again and hoping that this time, his father would appear to him and the experience would start to make sense.

He also trusted his friend, Dr. Gabor Maté, a fellow Hungarian Holocaust survivor, who led the therapy and had arranged the trip. Maté is perhaps best known for his book, In the Realm of Hungry Ghosts, which explores his work with extremely traumatized injection drug users in Vancouver. He's been offering psychedelic therapy to trauma survivors since learning about the potential of ayahuasca in 2008.

But he had traveled for 12 hours—via plane, boat, and finally on foot—to this primeval place, a newly-built gazebo-like wood platform without walls. He had expressed his intentions in a group therapy session in preparation; he had eaten a special, bland diet and even halted other medications.

Ketamine—the club drug, a.k.a. Special K—is already widely used for intractable depression, following a series of trials that showed it could act rapidly, unlike existing antidepressants, which often take weeks to have an effect.

These days, evidence of a psychedelic renaissance is everywhere in America. MDMA—best known as ecstasy, or, more recently, Molly—is set to begin Phase 3 clinical trials for the treatment of post-traumatic stress disorder (PTSD), which means it could be FDA-approved and on the market as early as 2021. Psilocybin, the active ingredient in magic mushrooms, is at a similar stage, with research suggesting it can help with the anxiety and depression associated with cancer, and with quitting smoking.

In fact, Sarlo first realized that he might be depressed when both of his daughters complained about his constant dissatisfaction when they were teenagers. "They would ask, 'Dad, how come you're not having fun ever? You never laugh,'" he recalls. It wasn't until he began to find himself weeping for no discernible reason that he finally sought help—and began a journey that would ultimately take him to places he did not think it possible to reach.

For much of his life, Sarlo suffered from one of depression's cruelest tortures: anhedonia , or the inability to feel pleasure. Anhedonia insidiously drains joy from formerly enjoyable social interactions and experiences—and worse, replaces it with dullness, dread, or apprehension.

Until recently, however, Sarlo wasn't able to fully enjoy the material pleasures of his wealth, like racing sailing yachts and a country house with its own vineyard in Marin County. Nor could he appreciate the deeper comforts of friends, romance or family. "I don't have many memories of looking at him and feeling like he was in joy," says his daughter Gabrielle, now 50.

He leads me out onto a wide terrace from which I can see cliffs, beach, surfers, and, in the misty distance, the Marin headlands and Mount Tamalpais. This is a long way from the dirt-floored home of his grandparents in Újfehértó, Hungary, and from the modest apartment of his parents—a textile factory clerk and a seamstress—in Budapest.

When he sees me slack-jawed at the beauty of the place, Sarlo, who is slim with intense blue eyes, smiles impishly and says, "Not bad for a refugee, eh?"

Sarlo is one of the key forces behind the scenes in this revolution, funding research and connecting various experts with each other and the resources they need to advance their work. "He's a nexus," says Dr. Maté. "He's important both in the sense that he's a donor and he makes things happen, but also, his house is a bit like a clearinghouse."

" Microdosing ," or taking such small amounts of these drugs that they don't noticeably alter consciousness, is fashionable in Silicon Valley and beyond. The psychedelic revival has such cultural currency that even the New Yorker got in on the action, running a snarky piece about ayahuasca use by Brooklyn hipsters.

Two widely-discussed recent books—Ayelet Waldman's A Really Good Day: How Microdosing Made a Mega Difference in My Mood, My Marriage and My Life and Steven Kotler and Jamie Wheal's Stealing Fire: How Silicon Valley, the Navy SEALs, and Maverick Scientists Are Revolutionizing the Way We Live and Work—tout the benefits of these substances for everything from depression and PTSD to improved creativity and productivity.

Meanwhile, a YouGov poll this month found that nearly two thirds of American adults would personally be willing to try MDMA, Ketamine, or Psilocybin if it was proven safe to treat a condition they have. And in April, a scientific conference on research about drugs that produce visions, out-of-body and transcendent experiences like ayahuasca, psilocybin and LSD was attended by over 3,000 people—including Tom Insel, the former director of the National Institute of Mental Health.

"For me, the most important thing is to find some of the tipping points," Sarlo says. "There are opportunities where relatively small amounts of money and energy can have a tremendous impact. So that's what I'm looking for. I hope I can spend all of my money, but I don't have enough opportunity."

Overall, Sarlo's main goal is to support research and find ways to de-stigmatize these medicines so that they can eventually be used legally, effectively, and safely, in appropriate contexts.

Jesse explains, "There's a certain sensibility to a successful venture capitalist. You have to find good sectors and projects that are going to work, while a lot of people are pitching you ideas that probably aren't going to work. Another thing George offers is his inclination toward funding partnerships." Sarlo has given $100,000 to Usona.

"He brings to the table a particular acumen," explains Bob Jesse, a former Oracle executive who is now a board member of the Usona Institute, a nonprofit organization that does what pharmaceutical companies usually do: in this case, funding, sponsoring, and managing trials of psilocybin, with the goal of supplying the market if a version of the drug does win approval.

According to Vicky Dulai, who runs Compassion for Addiction, one of Sarlo's charities, he has donated nearly two million dollars to psychedelic research so far—a substantial sum given that neither the government nor Big Pharma is willing to fund the studies needed to get these drugs to market.

The clash between science and spirituality that inevitably arises in the psychedelic world—and the politics that caused a backlash against the drugs in the 1960s and 70s—makes this a difficult undertaking, even for someone with such fabulous wealth. In the age of Donald Trump and attorney general Jefferson Sessions, fear about a return to the dark ages of drug war demonization of all currently illicit psychoactive substances is palpable.

Ayahuasca is a potent mixture that includes segments of the Banisteriopsis caapi vine boiled together with either Psychotria viridis (chacruna) leaves or those from the Diplopterys cabrerana (chagropanga) plant. By itself, each ingredient isn't strongly psychoactive. But when boiled together, an enzyme inhibitor in the "vine of the soul" allows the DMT from the leaves to profoundly alter consciousness.

Inside Sarlo's brain, a drug called DMT had presumably reached the receptors it targets, which are normally occupied by the neurotransmitter serotonin, involved in regulation of mood and sensation. Like the classic psychedelics LSD and psilocybin, DMT is active at one particular serotonin receptor, known as 5HT2A, which is believed to be responsible for the drug's mind-expanding effects.

"They are all covered with snow, except one skeleton is sticking out and for some reason I know it's my father," he tells me.

During his second ayahuasca experience, Sarlo's visions took him far away from the humid rainforest. This time, he says, he was transported to what appeared to be a snowy field at the edge of a wintry forest. Skeletal men stood like statues, frozen in marching formation. Some still wore remnants of the striped uniform of prisoners, signifying that they were Jewish men who had been conscripted to support the fascists in World War II.

Then, Sarlo says, "I ask the big question: 'Did you love me?'" His father indicated the skeleton that was most clearly sticking out; its mouth was open, as if to speak. And he said, "'Look at me. That's my last breath and with my last breath I blessed you and promised to guard you all of your life.'"

Tripping in Mexico, and sensing a presence next to him on that frozen field in Europe, which he knew intuitively to be his father's spirit, Sarlo asked the questions he'd been wrestling with for years. First, "Why didn't you say goodbye?" He says that he heard a familiar voice respond: "I didn't want to wake you. I thought I would be back the same day. I was known as a pretty clever guy. I thought: I can get out of this stuff."

Sarlo last saw his father when he was just four years old, in 1942. He remembers the last day he spent with him: He had watched his dad go pale as he read the telegram that told him he would be conscripted. But the next morning, when the elder Sarlo headed out the door, he didn't even wake his son for a farewell kiss. "I thought that he didn't come back because I was a bad boy," his son recalls. "That's what I carried with me."

"He felt lighter to me and in many ways, what transpired over the next few years in terms of our relationship was miraculous."—Gabrielle Sarlo

The brew has been used for millennia by South American peoples, and was brought to the attention of Western science by ethnobotanist Richard Schultes . American beatniks and psychedelic explorers first learned of it under its other name—Yage—in William Burroughs's and Allen Ginsberg's 1963 Yage Letters .

More remarkably, the transformation has persisted over the years since that initial experience. "He changed in so many ways," his daughter Gabby says. "He became kinder, more compassionate, more understanding of others, more open. He felt lighter to me and in many ways, what transpired over the next few years in terms of our relationship was miraculous… He's turned into the person that I had kind of always hoped to have as my dad."

Decades of accumulated trauma and depression started to lift. "I felt weak. I felt lighter. I felt relief. I can't say that I was happy, but I felt good," Sarlo says.

Suddenly, after that "interaction," years of pain began to dissolve and ebb away. The burden of feeling fatherless, unworthy, and unlovable; the fear that had dominated his childhood as a Jewish boy in Nazi-occupied Hungary, when every day brought new restrictions, starvation, crowding. The bomb that dropped into the courtyard but didn't explode; the incident in which he'd hidden under a man's coat on a train and watched a soldier's bayonet miraculously slide past him, without injuring him or causing him to cry out.

Modern science can study these age-old substances with great precision. But even if you're lying in an fMRI brain imaging machine surrounded by state-of-the-art technology while tripping, the only language that begins to describe what you feel is that of mysticism—and all the fuzzy spiritual stuff that hard scientists often dismiss as "woo."

Psychedelic research is fraught with paradox: for one thing, ingesting a chemical that clearly alters specific receptors in one's very physical and material brain can produce an experience that feels as though you have transcended time, space, your body—even the universe. A chemical transforms not just your brain, but your mind.

Maté, who uses ayahuasca in clinical work where it is legal, says, "People have all kinds of visions. I'm not ever concerned or engaged with their literal content, but with their emotional-spiritual message. They convey powerful truths, and my work is to help people identify and integrate those truths… For the purposes of the work, it doesn't matter what I believe."

But while medicine can easily incorporate new psychiatric drugs that show efficacy on validated scales, it will have a far more difficult time accommodating treatments that leave some patients believing they have communed with the dead, discovered the afterworld—or even met God. Medicine and religion are already the site of many fraught interactions: to bring a treatment into the mainstream, clinical trials and clear measures of progress are needed; otherwise, insurers and politicians will dismiss psychedelic therapy as sheer quackery.

"What really happens when we die? We don't know. Don't act like you do."—Roland Griffiths

"It's a great question," says Dr. Robin Carhart-Harris, who heads psychedelic research at Imperial College in London and has studied psilocybin for depression. "It's poignant. It's come up in our trial and it seems to come up for everyone. These apparent recollections feel so real."

This led him to research the history of the Hungarian slave laborers and the way they were likely to have died during the war—and he found nothing that falsified the scenario he experienced. His father could have died just the way he saw in his vision; it wasn't historically incorrect. On the other hand, freezing to death in a Northern European forest when you aren't given adequate food or clothing is not especially unlikely.

"The other part of me thought, There is some kind of a world beyond what we know."

For his part, Sarlo says that at first, part of him reasoned, "'OK, so this has been on your mind for many years. It accumulated all this yearning in your subconscious and when you took that medicine, something opened up and you saw and heard what you wanted to see and hear.'"

That leaves people who want to blend the scientific and the shamanic facing difficult questions. For example: Did George Sarlo really meet his father? And how much does the literal truth of these experiences even matter?

But Roland Griffiths, professor of psychiatry at Johns Hopkins, is less certain. "You're asking the unanswerable," he tells me. In 2000, Griffiths actually won US government approval to conduct the landmark study of psilocybin experience in healthy participants, which began the research renaissance in this field.

Mark Kleiman, professor of public service at New York University's Marron Institute and an expert on drug policy, doesn't view psychedelic experiences as "truth," even though he says the drugs have significant potential. "I'm still stuck in the Enlightenment," he says. "It matters." In other words, if many Americans are determined to reject "fake news" and "alternative facts," we need to separate religious ideas from empirical reality.

If someone forms a sincere belief about life after death in the context of healing from depression or trauma, Carhart-Harris adds, what counts most is that recovery and its robustness and longevity. He explains, "I think it has an emotional meaning and value that I wouldn't want to depreciate. But equally, I wouldn't want to lose my scientific integrity by sort of playing into the experience and saying that it's real."

Carhart-Harris agrees that therapeutically, the reality of the content of the vision doesn't matter all that much. "Even though I don't believe that he transcended time and space, I do believe that the experience is of George's mind, and I also believe it's meaningful."

For example, there is ongoing research aimed at developing a drug that would have the same depression-lifting effect of ketamine, but without the out-of-body trip. (Success here would also have the financially convenient effect of creating products that—unlike existing psychedelics— could be patented.) Johnson & Johnson, Naurex, and AstraZeneca have all been testing such drugs.

The pharmaceutical industry and government agencies like the National Institute on Mental Health are betting these are mere side effects. In other words, they are trying to develop new medications that have the lasting healing effects of psychedelics without the ordeal or mystical experience recreational users have tended to seek.

Another important and more practical question is raised by the visions and emotions people report while under the influence of these drugs. That is, does the psychological experience of feeling as though you have, say, healed your relationship with your father actually cause brain changes that lead to psychological recovery—or is that just a side effect of pharmacological alterations in brain receptors, which make the real difference?

"What are we doing here, anyway? How did we come to be conscious? What really happens when we die? We don't know. Don't act like you do. So, I'm very comfortable even as a scientist to say there are things we simply don't know. I'm willing to rest in the mystery."

"Encountering one's deceased relative is a variation of the mystery of what happens upon death," he says, noting how the same types of reports are common in near-death experiences. He acknowledges that reductionists interpret such an experience as a psychological response generated by the brain, but in fact, he says, the mystery of consciousness remains.

For example, in a study that used psilocybin to help smokers quit, success was strongly linked with having a complete mystical experience. In this research, 80 percent successfully quit smoking—a rate that is far higher than seen with other methods.

These features include feeling a sense of "oneness" with others and the universe, a dissolution of the self ("nonduality"), a feeling of awe or sacredness, the sense that time and space have been transcended, an experience of great peace, bliss, and calmness—and an overwhelming sense that what has occurred is meaningful and represents a deep truth.

This suggests that the emotional experience, its psychological content, and the way you make meaning out of the trip may really matter. Several studies now show that people who have the most intense elements of a "mystical" experience during psychedelic sessions are more likely to experience positive change.

But many of the psychedelic researchers think this quest is unlikely to bear fruit: indeed, so far , ketamine-like compounds without trippy effects haven't reliably beaten placebo.

Lisa Monteggia, professor of neuroscience at the University of Texas Southwestern Medical Center in Dallas, has studied how ketamine works to fight depression. Based on her own research, she thinks the trippy effects can be dissociated from the therapeutic ones. The right dose of the right compound, correctly timed, could "enable the design of treatment strategies against neuropsychiatric disorders without the unwanted side effects of these drugs," she tells me.

In fact, one possible explanation of how these drugs work could bridge the psychology of the experience and the neuroscience of receptor change. The idea is that the receptor changes temporarily allow conscious access to part of what you might call the brain's "operating system," (OS) which is normally inaccessible.

"I think the core factor here is, 'Is the mind being loosened?'" he adds. "Even with micro-dosing and with the higher doses, it's all about a loosening of mental constraints—and with that loosening… an enhanced possibility for insight."

"I think it's wishful thinking," agrees Carhart-Harris. However, he notes that reports about mood lifting effects of "micro-dosing" do suggest that at least some change may be possible without a full-blown trip.

"It's theoretically possible, but it strikes me as being improbable," Griffiths says of the idea of taking the "trip" out of psychedelic medicine. "Part of the nature of the experience that people have and the way people explain why they change has to do with their interpretation and the meaning of the experience… so this is very much about meaning-making."

Similarly, research on psilocybin use for anxiety and depression associated with terminal cancer also found a strong link between feeling these mystical emotions and long-term reduction in distress. And a study of ketamine found that greater "out of body" feelings were linked with better odds of depression relief.

This part of the OS includes ideas and beliefs we adopted as children to make sense of the world, which structure how we experience everything that follows. If these beliefs are harmful—perhaps shaped by trauma or otherwise distorted—accessing them during a vision might help integrate and update them in a way that leads to lasting change.

By the mid-1960s, over 1,000 papers had been published on LSD alone before increasing levels of recreational use by hippies sparked a worldwide panic and an international ban. Even though much of this data did not meet the standards used today, it did show promise, suggesting that psychedelic therapy could potentially have lasting positive results on those suffering from alcoholism and other addictions, as well as anxiety related to cancer.

Crucially, today's studies suggest fears about long-term damage from the classic hallucinogens like LSD and psilocybin are overblown, and relate to use of inappropriate doses in uncontrolled settings without careful preparation and support during and afterwards.

"There certainly are risks and it's important not to minimize those risks," says Griffiths. "But they are not as devastating or prevalent as would have been imagined based on the media coverage and the cultural impressions that emerged from the 1960s." A common fear, for many, is that they will experience hell rather than heaven—coming away not with a sense that the universe is benign and kind, but instead overwhelmed by an encounter with a howling existential void in which life is pointless and fate is cruel. Griffiths himself had concerns about inducing such experiences, particularly when treating dying people. "I had a lot of trepidation," he says, despite the positive reports in the earlier literature. Being depressed and anxious about impending death would seem to be a set-up for such a bad trip—or what researchers prefer to call a "challenging experience." "You would think that people with life-threatening cancer would be deeply primed for that, but in fact, what frequently occurred among patients in our study were experiences of deep meaning, connection and integration," Griffiths says, adding, "That's another mystery." Although many study participants have transient fear and even terror, less than 1 percent reported any lasting issues, according to Griffiths—and those problems that were reported were not severe.

Nonetheless, researchers and supporters like Sarlo recognize that it is important not to let hype and hope overrun data. After all, a massive cultural backlash like the one that ended nearly all research on these substances for decades is always a possibility, as the history of American drug policy and psychiatry makes clear.

"Every new treatment in the history of psychiatry, going back thousands of years, does very well at the beginning, then doesn't do so well," explains Dr. Allen Frances, professor emeritus at Duke who chaired the DSM-IV task force that categorized diagnoses in psychiatry in the 1990s.

"Original hype will always exaggerate the potential benefits and minimize very realistic risks," he says. "It's certainly promising enough to have careful study" of the emerging data on psychedelic medicine, he adds, before cautioning that what works well in small, selected samples can also do serious harm if misused by a larger, unscreened group. He has particular concerns about how ketamine is already being widely used for depression, without larger, longer, and higher quality trials on repeated use.

For his part, Sarlo wants to help other people find the relief he's experienced. He's realistic about the advantages he enjoys and the importance of the therapeutic context and ability to integrate insight into normal life to the effectiveness of these drugs. Still, his story raises the question: If a skeptical venture capitalist with a degree in electrical engineering can overcome decades of Holocaust-related trauma by careful use of these medicines, what else might they be able to do?

To prevent harm or backlash, careful science and caution is essential. But these days, the need for remedies that can decrease selfishness and maximize empathy and kindness is more urgent than ever.

"I think psychedelics should be seen as a kind of 'transformative medicine,'" Sarlo says. "They really do have the potential to change the world."

Follow Maia Szalavitz on Twitter.