What made the Oracle at Delphi special? Some researches have stressed a trance-like state the Pythia entered into, so that she babbled incoherently, while the prophet or spokesman rendered the gibberish into a coherent reply for the questioner. Other researches have downplayed the mystical or paranormal aspects of the experience.[12] Yet Plutarch makes a point of potent vapors that arise from the adyton: “It is a fact that the room in which they seat those who would consult the god is filled, not frequently or with any regularity, but as it may chance from time to time, with a delightful fragrance coming on a current of air which bears it towards the worshippers, as if the source were the holy of holies; and it is like the odour which the most exquisite and costly perfumes send forth.”[13] Plutarch, who was himself the high priest of Delphi in the late first century AD, wrote three dialogues about the oracle. He records that according to legend, a shepherd named Coretas had fallen into a fissure, which inspired him to make divine pronouncements, perhaps caused by exhalations from the earth.[14] Because of the sacredness of the place, the temple of Apollo was built over the location of Coretas’ fall.
A remarkable study led by a geologist and an archaeologist has now shown that the peculiar story about vapors from the earth has a firm basis in science.[15] The limestone formations of Mount Parnassus are porous. The temple site, and in particular the sacred precinct of the adyton, sits right at the intersection of two fault lines. Deep in the mountain are deposits of bitumen that, when exposed to even moderate heat, release volatile hydrocarbons, which are then carried upward through the fissures. Ethane and methane, odorless gases found in natural gas, and ethylene, a fragrant gas, are released by the process. Ethylene, moreover, has psychoactive properties and has been used on dental patients as an anesthetic. In small doses it produces euphoria and a kind of intoxication. It is not habit-forming, and its effects wear off soon after exposure ceases. In larger doses it can cause bad side-effects, such as the hysteria the Pythia once experienced in a famous episode.[16]
Plutarch wondered why the oracle in his time usually answers questions in ordinary language rather than in verse.[17] He noted that the vapors rising from the earth occurred only occasionally. It may be that shifting geological patterns had slowly robbed the oracle of the exhalations that brought the ecstatic utterances of the past. But the priestess was attended by a prophētēs, a prophet, or rather, a spokesman, who may have embellished the answers, and possibly scribes may have versified answers ex post facto.[18] No doubt rational processes — as well as political pressure and monetary influence — played some role in the giving of oracles. But the trances of the Pythia seem to have been quite real and to have had a source in the depths of Mount Parnassus on the site Coretas stumbled into.
[12].See especially Fontenrose 1978:196-239.
[13].Plutarch The Obsolescence of Oracles 50 = Moralia 437c, trans. Babbitt.
[14].Plutarch The Obsolescence of Oracles 42 = Moralia 433c-d. On the influence of the vapors, see ch. 48.
[15].On the researches of geologist Jelle de Boer and archaeologist John R. Hale, see Broad 2006:131ff.; Hale et al. 2003.
[16].Plutarch The Obsolescence of Oracles 51 = Moralia 438b-c.
[17].The Oracles at Delphi = Moralia 394d ff.
[18].Strabo 9.3.5; Plutarch The Oracles at Delphi 25 = Moralia 407a-b; The Obsolescence of Oracles 51 = Moralia 438b; Bowden 2005:33-38; Fontenrose 1978:212-215; Amandry 1950:120-123, 167-168.