EARTH, Laniakea Supercluster—For nearly two thousand years, some of the greatest minds in Western civilization met in a torch-lit hall at the Greek pilgrimage site Eleusis to drink a cryptic barley beverage called kykeon, quietly prepared and dispensed by specialist priestesses, in an initiation rite meant to confront the concept of one’s own mortality.

Plato did it. Cicero did it. Roman emperors did it. Under the penalty of such death, all were prohibited from mentioning what happened inside.

For generations, it was known only as the Mysteries.

Now, a team of Greek and international researchers may have finally cracked the recipe of the long-mysterious elixir. A study published in Scientific Reports in February demonstrates for the first time that ancient Greek priestesses could have deliberately converted a toxic grain fungus into a mind-altering psychedelic compound using nothing more than wood ash and water—technology readily available three millennia ago. The research was led by scientists at the National and Kapodistrian University of Athens, in collaboration with the University of Granada and Boston University.

The researchers collected ergot (Claviceps purpurea), a parasitic fungus that infects barley. Untreated ergot is devastatingly dangerous, believed to be responsible for the medieval plague known as St. Anthony's Fire, which caused convulsions, gangrene, and mass death across Europe. It also, coincidentally, produces alkaloids chemically related to LSD.

So even with that toxicity, the idea that ergot sat at the heart of the mystery never went away.

In 1978, the “Psychedelic Eleusis” hypothesis was laid out in The Road to Eleusis, a book co‑authored by the chemist who first synthesized LSD, Albert Hofmann, classicist Carl A. P. Ruck, and controversial banker‑turned‑ethnomycologist R. Gordon Wasson, who publicly exposed the secret indigenous ritual use of so-called magic mushrooms to the masses in a 1957 Life magazine article about Mazatec healer Maria Sabina.

Drawing on ancient texts, comparative religion, and ergot pharmacology, they argued that the enigmatic kykeon was quietly spiked with ergot alkaloids and that a carefully managed psychedelic experience powered the Mysteries.

The problem, critics argued, was toxicity, citing how untreated ergot can cause convulsions, gangrene, and death. Therefore, if the drink really contained ergot, serving it to thousands of initiates over centuries should have produced a mass poisoning event, not a spiritual awakening.

The new study directly addresses that objection.

The team pulverized ergot sclerotia, then boiled the powder in lye (an alkaline solution made from wood ash dissolved in water). After two hours at a pH of 12.5, high-resolution chemical analysis showed that all toxic ergopeptides had been completely broken down. What remained were lysergic acid amide (LSA) and its isomer, iso-LSA, which are psychoactive compounds capable of inducing altered states of consciousness, but far less potent than LSD.

"The central question was whether toxic ergot could realistically have been processed into something psychoactive but not lethal using methods available in antiquity," Evangelos Dadiotis, a pharmaceutical scientist at the University of Athens and co-lead author of the study, told Live Science.

"We used a simple lye preparation made from water and ash, a technology well known in the ancient world."

The yields were precise: approximately 0.54 milligrams of LSA and 0.48 milligrams of iso-LSA per gram of ergot, according to the published study. The researchers note that only a few kilograms of processed ergot would have been needed to supply ceremonies at the Telesterion, the vast initiation hall at Eleusis, where an estimated 2,000 people could be initiated each year.

Archaeological evidence adds another layer of plausibility. At Mas Castellar de Pontós, a Greek colonial site in Spain with a sanctuary dedicated to the Eleusinian goddesses, researchers previously discovered fragments of ergot inside a ceremonial vessel and embedded in the dental calculus of a 25-year-old man buried at the site.

Not everyone is ready to declare the mystery solved, though. Sharday Mosurinjohn, a religious studies scholar at Queens University in Ontario who was not involved in the research, told Live Science that the study demonstrates "chemical feasibility within a plausible ancient technological context," but cautioned that "chemical feasibility is not historical proof."

That's a fair point. No vessels from the Telesterion itself have ever been chemically analyzed, and no systematic residue search has been conducted at the actual ruins of Eleusis.

But the study lands at a moment when psychedelic research is experiencing a mainstream resurgence, with clinical trials exploring psilocybin and LSD analogs for depression, PTSD, and end-of-life anxiety. The idea that an ancient civilization may have institutionalized something similar around confronting death isn’t so fringe anymore.

The Eleusinian Mysteries ran from roughly the 15th century BCE until the sanctuary was destroyed in the late 4th century CE during the Christianization of the Roman Empire. Initiates kept their vow of silence for all those centuries. Modern chemistry, it turns out, has no such obligation.