Victoria Grossack: If you visit Delphi today – a few hours by car from Athens – you will be treated to spectacular ruins in a stunningly beautiful setting. Even on a very hot day – and there are plenty of hot days in Greece – the breezes and the mountains give the place an aura of serenity. You can see the amphitheater, the marble columns, and the treasuries where various city-states sent offerings to be put on display. There is also one spot, underground, where the Pythia – the priestess of the oracle - sat on a tall tripod, breathed in the prophecy-enabling vapors coming out of the earth, and muttered. Her mutterings were then reinterpreted by a priest as an answer to the petitioner who had posed his question. Why was this place revered? Did it have any truly prophetic qualities? Why are people fascinated by oracles, even today?
Sniffing in all that Sulphur Dioxide ("Vapours") will make anyone hallucinate and go into a trance. The "interpretations" were more obviously a religious device to extract as much money as possible from the Petitioner IMO.