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Oracle at Delphi May Have Been Inhaling Ethylene Gas Fumes
Theory of priestess's trance state captures public's imagination
by Erowid
v1.1 - May 2007
Articles originally published in online news sources
Citation:   Erowid. "Oracle at Delphi May Have Been Inhaling Ethylene Gas Fumes: Theory of priestess's trance state captures public's imagination". May 2007; v 1.1. Available from
The findings of several researchers in the late 1990s and early 2000s appeared to corroborate Classical Greek accounts of divinatory ceremonies at Delphi. The Greek author Plutarch, in the first century C.E., wrote about the Oracle (also known as the Pythia), a succession of priestesses of Apollo who figured prominently in Greek culture for over a thousand years. Plutarch described how a woman would enter a small chamber ("adyton") in the temple of Apollo and inhale sweet-smelling vapors ("pneuma") from a fissure in the mountain before entering a trance. From this state, she would provide responses to seekers' inquiries posed to her by the intermediary of priests, who interpreted her pronouncements for them. Other ancient texts mention mysterious vapors at the temple site at Delphi, as well as the priestess's trance states. At least one portrayal of the Oracle painted on pottery could be interpreted in support of the written texts.

At the turn of the 20th century, writers covering the first major archeological excavation at Delphi dismissed the "pneuma" stories as fable. Findings from later geological and chemical analyses appeared to support the view that the Oracle may have inhaled naturally occurring ethylene (ethene) gas as part of the ceremony. The research1 compiled is compelling, and received favorable coverage in the scientific and popular press.2,3,4,5

Given that measuring actual ethylene levels present at the temple site over 2000 years ago is impossible, the explanation is likely to remain speculative.

Recent critics6,7 of the ethylene theory have pointed out further issues. Foster and Lehoux, 2007, "argue that both the empirical evidence and the argument mustered by the de Boer team for the ethylene-intoxication hypothesis are inadequate for two reasons. The first reason is scientific: the concentrations of ethylene identified by de Boer, Hale, et al. would have been insufficient to cause a trance-like state. The second reason is historical and philosophical: the evidence and argument presented to link the mantic behavior of the Priestess to ethylene intoxication is dubious. In the conclusion, we suggest that this tenuous argument was widely propagated because it appealed to essentially positivist inclinations and sentiments in the science-reading public. Its conclusions appealed to these inclinations so effectively that readers did not notice the weak evidence and problematic argument mustered to support the conclusion." (Foster J, Lehoux D. 2007)

A sampling of related media account: #
  1. Fumes and Visions Were Not a Myth for Oracle at Delphi
    by William Broad, Mar 19, 2002
    © 2002, (article no longer publicly available at

    For at least 12 centuries, the oracle at Delphi spoke on behalf of the gods, advising rulers, citizens and philosophers on everything from their sex lives to affairs of state. The oracle was always a woman, her divine utterances made in response to a petitioner's request. In a trance, at times in a frenzy, she would answer questions, give orders and make prophecies.

    Modern scholarship long ago dismissed as false the explanation that the ancient Greeks gave for the oracle's inspiration, vapors rising from the temple's floor. They found no underlying fissure or possible source of intoxicants. Experts concluded that the vapors were mythical, like much else about the site.

    Now, however, a geologist, an archaeologist, a chemist and a toxicologist have teamed up to produce a wealth of evidence suggesting the ancients had it exactly right. The region's underlying rocks turn out to be composed of oily limestone fractured by two hidden faults that cross exactly under the ruined temple, creating a path by which petrochemical fumes could rise to the surface to help induce visions.

    In particular, the team found that the oracle probably came under the influence of ethylene -- a sweet-smelling gas once used as an anesthetic. In light doses, it produces feelings of aloof euphoria.

    "What we set out to do was simple: to see if there was geological truth to the testimony of Plutarch and the others," said Dr. Jelle Zeilinga de Boer, a geologist at Wesleyan University, who began the Delphic investigations more than two decades ago.

    As is often the case in science, the find was rooted in serendipity, hard work and productive dreaming. At one point, not unlike the oracle herself, the scientists were stimulated in their musings by a bottle of Dão, a Portuguese red wine.

    The team's work was described last year in Geology, a publication of the Geological Society of America, and at the annual meeting in January of the Archaeological Institute of America. It will also be reported in the April issue of Clinical Toxicology.

    Over the years, scholarly doubt about the thesis has given way to wide acceptance and praise.

    "I was very, very skeptical at first," said Dr. Andrew Szegedy- Maszak, a Wesleyan colleague and classicist, who specializes in Greek studies. "But they seem to have it nailed. I came to scoff but stayed to pray."

    Near the Gulf of Corinth on the slopes of Mount Parnassus, the religious shrine was founded before 1200 B.C. and the temple eventually built there became the most sacred sanctuary for the ancient Greeks. They considered it the center of the world, marking the site with a large conical stone, the omphalos (meaning navel or center).

    Originally a shrine to Gaea, the earth goddess, the temple at Delphi by the eighth century B.C. was dedicated to Apollo, the god of prophecy. His oracle spoke out, often deliriously, and exerted wide influence. One of her admired pronouncements named Socrates the wisest of men.

    Before a prophetic session, the oracle would descend into a basement cell and breathe in the sacred fumes. Some scholars say her divine communications were then interpreted and written down by male priests, often in ambiguous verse. But others say the oracle communicated directly with petitioners.

    With the rise of Christianity, the temple decayed. The Roman emperor Julian the Apostate tried to restore it in the fourth century A.D., but the oracle wailed that her powers had vanished.

    French archaeologists began excavating the ruins in 1892, in time digging down to the temple's foundations. No cleft or large fissure was found. By 1904, a visiting English scholar, A. P. Oppé, declared that ancient beliefs in temple fumes were the result of myth, mistake or fraud.

    The Oxford Classical Dictionary in 1948 voiced the prevailing view: "Excavation has rendered improbable the postclassical theory of a chasm with mephitic vapours."

    Another round of myth-busting came in 1950 when Pierre Amandry, the French archaeologist who helped lead the temple excavations, declared in a book on Delphi that the region had no volcanism and that the ground was thus unable to produce intoxicating vapors.

    Three decades later, in 1981, Dr. de Boer went to Delphi not to study old puzzles but to help the Greek government assess the region's suitability for building nuclear reactors. His main work was searching out hidden faults and judging the likelihood of tremors and earthquakes.

    "A lucky thing happened," he recalled. Heavy tour traffic had prompted the government to carve in the hills east of Delphi a wide spot in the road where buses could turn around, exposing "a beautiful fault," he said. It looked young and active.

    On foot, Dr. de Boer traced it for days, moving east to west over miles of mountainous terrain, around thorny bushes. The fault was plainly visible, rising as much as 30 feet. West of Delphi, he found that it linked up to a known fault. In the middle, however, it was hidden by rocky debris. Yet the fault appeared to run right under the temple.

    "I had read Plutarch and the Greek stories," Dr. de Boer recalled. "And I started thinking, `Hey, this could have been the fracture along which these fumes rose.' "

    Dr. de Boer put the idea aside. Knowing little of the archaeological literature, he assumed that someone else must have made the same observation years earlier and come to the same conclusion.

    In 1995, he discovered his mistake. While visiting a Roman ruin in Portugal, he met Dr. John R. Hale, an archaeologist from the University of Louisville, who was studying the Portuguese site. At sunset, the two men shared a bottle of wine, and the geologist began telling the archaeologist of the Delphi fault.

    "I said, `There is no such fault,' " Dr. Hale recalled. But Dr. de Boer convinced him otherwise. He cited both Plutarch, a Greek philosopher who served as a priest at Delphi, and Strabo, an ancient geographer. Each told of geologic fumes that inspired divine frenzies, with Plutarch noting that the gases had a sweet smell. By the end of the evening, the geologist and archaeologist had decided to work together to find the truth.

    Back in the United States, Dr. Hale tracked down the original French reports on the temple excavation and discovered to his surprise notations that the bedrock on which the temple was built was "fissured by the action of the waters."

    The French archaeologists, expecting a yawning chasm, had apparently overlooked the importance of the small cracks.

    "What I had been taught was wrong," Dr. Hale recalled. "The French had not ruled it out."

    By 1996, the two men had traveled to Greece to resurvey the fault at Delphi and study the regional maps of Greek geologists. These revealed that underlying strata were bituminous limestone containing up to 20 percent blackish oils.

    "I remember him throwing the map at me," Dr. Hale said of Dr. de Boer. " `It's petrochemicals!' " No volcanism was needed, contrary to the previous speculation. Simple geologic action, Dr. de Boer insisted, could heat the bitumen, releasing chemicals into temple ground waters.

    During a field trip in 1998, the vent notion grew more plausible still as the two men discovered a second fault, which they named Kerna after a well-known spring, going north- south under the temple. The intersecting faults now marked a provocative X.

    As intriguing, the second fault appeared to be aligned with a series of ancient dry and modern wet springs, one directly beneath the temple.

    The scientists found that the dry springs were coated with travertine, a rocky clue suggesting that the waters had come from deep below. When hot water seeps through limestone, it leaches out calcium carbonate that stays in solution until it rises to the surface and cools quickly. The calcium carbonate can then precipitate to form rocky layers of travertine.

    Increasingly excited, the two men won permission from the Greek authorities to sample the travertine.

    At this point, Dr. Jeffrey P. Chanton, a geochemist at Florida State University, joined the team. He analyzed the travertine samples gathered from dry springs near the temple and in its foundation, finding methane and ethane. Each can produce altered mental states. But a better candidate soon arose.

    "A small light went off in my mind," Dr. de Boer recalled. Perhaps, he speculated, ethylene had been there as well.

    Ethylene is significantly less stable than ethane and methane, so its absence in old rocks was understandable. Yet psychoactively, ethylene is quite potent, more so than ethane, methane or even nitrous oxide. From the 1930's to the 1970's, it was used for general anesthesia.

    Dr. Chanton went to Greece, sampling an active spring near the temple.

    The team waited. Days passed. Then his call came in. He had found ethylene, as well as methane and ethane. To all appearances, the ancient riddle had been solved.

    In late 2000, Dr. Henry A. Spiller, the toxicologist who directs the Kentucky Regional Poison Center, joined the team to help with the pharmacological analysis.

    "There's a fair amount of data on the effects of ethylene," Dr. Spiller said. "In the first stages, it produces disembodied euphoria, an altered mental status and a pleasant sensation. It's what street people would call getting high. The greater the dose, the deeper you go." Once a person stops breathing ethylene, he added, the effects wear off quickly.

    Modern teenagers know of such intoxicants, including ones that in overdoses can kill. Experts say that youths who breathe fumes from gas, glue, paint thinner and other petrochemicals are toying with hydrocarbon gases.

    Of late, Dr. Hale has been widening his focus, investigating other ancient Greek temples that he believes were built intentionally on geologically active sites.

    And Dr. de Boer, now 67, is still concentrating on Delphi. On March 9, he and some students left for Greece to drill out rocky samples from the fault zones and illuminate them under a special light to try to establish dates of seismic activity.

    Such geologic shocks, he said, may have influenced fume production over the ages, causing the intoxicating gases to wax and wane.

    "You never know if it will work," he said of any research project shortly before the Delphi trip. "With the fumes, it did. With this, we don't know. But it's worth a try."

  2. Oracle's Secret Fault Found:
    Ancient prophesies made at Delphi may have been inspired by natural gas
    by Philip Ball, Jul 17 2001
    © 2001, (article no longer publicly available at

    The Temple of Apollo: hot air at fault for the oracle.

    The Greeks and Romans took their prophesies from a woman who was high on the fumes of natural gas, say US geologists[1]. Geological surveys of the site of the Greek Temple of Apollo in Delphi reveal that the temple ruins lie over a fault cross that emits intoxicating vapours.

    The oracle at Delphi made the site a major religious centre for 2,000 years. Greek and Roman rulers flocked there, seeking advice on private and political affairs. The oracle was originally sacred to the Earth goddess Gea; later, a temple was dedicated to the Greek god Apollo. The oracle was finally forbidden in AD 392 by the Christian emperor of Rome.

    The Greek writer Plutarch, who, in the first century AD, served as a high priest of the temple, left clear records of how the oracle worked. It was spoken by a local woman - the Pythia - who entered a trance inside a small chamber, called the adyton. These trances occasionally deepened into delirium, even death.

    In the adyton, Plutarch says, the Pythia inhaled vapours from a fissure or spring. He describes the fumes as sweet-smelling, like perfume. Despite his priestly role, Plutarch was canny about the origin of the gases, speculating that they issued from the rocks below and might be affected by nearby earthquakes.

    But when the temple was excavated in the nineteenth century, archaeologists found no fissure or vapour emissions, leading some to wonder whether the legendary intoxicating fumes may have been inspired by other nearby geological features.

    Last year, geologist Luigi Piccardi in Florence, Italy, suggested that the idea for the myhthical chasm might have been prompted by a rupture opened up by a massive earthquake in the region, similar to the one in 373 BC that destroyed nearby cities on the Gulf of Corinth[2].

    Now Jelle de Boer of Wesleyan University in Connecticut, USA, and co-workers have discovered a previously unknown geological fault passing straight through the Sanctuary and Temple of Apollo. The fault is punctuated by active and dried-up springs. Indeed, there was an ancient spring house in the sanctuary right on the fault line.

    The new-found fault crosses the long-known Delphi fault, apparently right below the temple. This crossing makes the bitumen-rich limestone there more permeable to gases and groundwater.

    Seismic activity on the faults could have heated up these deposits, releasing light hydrocarbon gases, the researchers speculate. Indeed, water from a spring northwest of the temple contains methane, they report - and, even more intriguingly, traces of ethylene.

    Ethylene, a sweet-smelling gas, stimulates the central nervous system - it was once used as an anaesthetic. Although fatal in large quantities, small doses produce a floating sensation and euphoria. In other words, just what an oracle needs to start having visions.


    • De Boer, J. Z., Hale, J. R. & Chanton, J. New evidence of the geological origins of the ancient Delphic oracle (Greece). Geology, 29, 707 - 710, (2001).
    • Piccardi, L. Active faulting at Delphi, Greece: seismotectonic remarks and a hypothesis for the geologic environment of a myth. Geology, 28, 651 - 654, (2001).

  3. The Oracle of Delphi - High on Ethylene?
    Possible source of gases
    July 25, 2000
    © 2000, (article no longer publicly available at

    The ancient oracle of Delphi, in Greece, worked like a telephone psychic: Someone in need of advice could call on the priestess and get a rambling prophecy. And now the oracle has some science on its side.

    The priestess reportedly had visions after inhaling fumes that rose from a chasm beneath the temple at Delphi. But until now scholars rejected the testimony of the ancient writers because no one had ever found the cleft or the gases. Scientists have recently discovered two geological faults, intersecting directly under the temple at Delphi, which could have created a chasm during an earthquake.

    Moreover, geologists have measured hallucinogenic fumes rising from a nearby spring, and narcotic gases preserved within the temple rock.

    "Everything fits with the ancient writers being correct," said Jelle de Boer, a geophysicist at Wesleyan University in Middletown, Conn. "It shows again that many legends have some truth in them."

    An Italian geologist has also suggested that the chasm may have been a relic of an ancient earthquake. Luigi Piccardi, of the National Research Agency in Florence, published his conclusions in this month's issue of Geology.

    The Delphic oracle held sway over the Greek religious world for nearly two millennia, from at least 1400 BC to AD 381. Traditionally, she sat on a tripod over the cleft, waving laurel branches while gripped by the spirit of prophecy. Different women held the position of oracle, but all were believed to be the divine mouthpiece for Ge, the Earth mother, and later for Apollo.

    The ruins of Apollo's temple, which has been destroyed and rebuilt several times, still stand outside the modern village of Delphi, at the foot of Mount Parnassus.

    A herdsman reportedly discovered the vapours millennia ago. His goats acted strangely as they grazed near a fissure; coming closer, he breathed in the fumes and entered a prophetic state. A good place for a temple, the locals decided.

    Geologists aren't surprised by Delphi's unusual qualities. It lies on the north side of the Gulf of Corinth, an area riddled with faults and often wracked by powerful earthquakes. Two giant plates of Earth's crust converge on the Mediterranean, cracking and straining the ground around Corinth.

    Several years ago, de Boer established the behaviour of a fault running east to west beneath the temple. More recently, his group discovered that a second fault runs from north to south.

    And where the faults cross, a chasm could have formed. French archeologists excavated the temple earlier this century and found no sign of a chasm, but they didn't dig all the way down to bedrock, de Boer said.

    If they had, they might have discovered evidence of recurring earthquakes, each of which could release a new burst of gases from the depths. For instance, the earthquake that destroyed the Delphi temple in 373 BC may have caused one of the most powerful breaks along the east-west fault, Piccardi proposes in his paper.

    Meanwhile, de Boer's team has chiselled samples of travertine, a calcium-rich rock deposited by springs, from a temple wall. The travertine held tiny bubbles of ancient methane and ethane gas -- both of which would have come from the depths and can have slight narcotic effects.

    Even more compelling, de Boer said, a nearby spring still releases small amounts of ethylene, a sweet-smelling gas once used as an anesthetic. Higher doses can act as a mild narcotic, inducing a dream-like state without causing fainting -- just what the oracle may have experienced, he said.

    De Boer now hopes to identify the carved stones used to channel fumes directly to the oracle.

    Science can never determine exactly how the oracle made her prophecies, de Boer acknowledged. But it can show the ingredients to back up the legend really exist.

Revision History #
  • v1.0 - Mar 2002 - Erowid - Published on
  • v1.1 - May 2007 - Erowid - Updated to reflect speculative nature of ethylene theory, loss of publicly available offsite links.