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No. 1697:
Delphic Oracle

Today, the oracle speaks. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

The ancient Oracle at Delphi, we are told, transmitted prophesies that came up from Earth's belly. The ancient Mycenaeans had worshipped the Earth-goddess Gaia when they lived there. The Dorians built the Oracle's shrine in the eighth century BC, and, for them, Delphi was the Earth's ompholos -- its navel, or its center.

That holy place flourished for over a thousand years. Occasional armies fought over it, and Apollo replaced Gaia as the source of prophecy. During the age of imperial Rome, the Oracle finally lost its power, and the shrine became only a curiosity. But how could something that was only superstition lose the efficacy it never had? Now, New York Times science writer William Broad offers an answer.

First, let's see how the Oracle worked. The prophecies were uttered by a woman called the Pythia. She had to be over fifty and of blameless character. The Pythia first descended into a basement chamber and breathed the sacred fumes of Apollo. Then she returned and sat upon a stool. Holding a shallow basin of water in one hand and an olive sprig in the other, she would cry out her prophecy. Some scholars believe she was incoherent -- that priests wrote her utterance into verse form for the petitioner.

All this suggests that some sort of subterranean vent brought up hallucinogenic vapors that put the Pythia into a trance state. But Delphi sits at the base of Mount Parnassus with a spectacular view of the Gulf of Corinth. Despite occasional earthquakes, the setting is pretty stable. Geologists could find no large fault in the earth, and historians had long since debunked the vapor idea.

At least they had until a geologist named de Boer came in to assess the suitability of the region for installing nuclear reactors. Like other twentieth-century scientists, he found no evidence of faults in the area. But, just then, a moment of serendipity: crews were cutting into the hillside along the road, creating a turnout for buses bringing visitors to the old temple ruins.

De Boer noticed that they'd exposed a fissure, which reached out under the ruins. There was a vent after all. In fact, French archeologists had also written about it. But they'd discounted it because they expected a large fault. Then it turned out that Roman historians Plutarch and Strabo had both written about the fissure and the fumes. Plutarch had even said the vapors had a sweet smell.

De Boer and the archeologists who followed him found that two narrow fissures, carved by spring water, converged below the temple. Those fissures tied into subterranean petrochemical deposits. It's now pretty clear that the Delphic Pythia prepared herself by inhaling the sweet-smelling light hydrocarbon ethylene -- which, a scant sixty years ago, served hospitals as a general anesthetic.

That Delphic Oracle is a grim reminder of how easily we shape belief around ambiguous predictions. Like Macbeth, the moment we accept any prediction, we take the first step toward making it come true. We need to be very careful which fortune cookie we read!

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

Broad, W., For Delphic Oracle, Fumes and Visions. New York Times, Science Times, Tuesday, March 19, 2002. pp. D1, D4.

Harbur, J., The Atlas of Sacred Places: Meeting Points of Heaven and Earth. New York: Henry Holt and Company, 1994, 194-201.

de Jongh, B., The Companion Guide to Mainland Greece. Woodbridge, England: Boydell & Brewer Ltd., 1996, Chapter 7, "Delphi."

Ethylene is the very light unsaturated hydrocarbon, C2H4.