Opposite from common belief, Pythia was not one person, but the title of every priestess delivering the prophecies. There were three Pythias at the height of the Delphic Oracle.
At the beginning, when there was only one priestess Pythia , the prophecies were given once per year, on the 7th day of Vitsios Month (end of February beginning of March). Later, at the peak time, the oracles were pronounced on the seventh day of each month, except for the three winter months.
There was a particular ritual taking place before the delivery of the oracle. First, Pythia was cleansing herself at the Castalia Spring, and the priests were sacrificing an animal to the God. Then Pythia was taking her position in the middle of the temple, called Adyton, sitting on the Holy Tripod and was burning leaves of laurel.
Then Pythia had to drink water from the Castalia spring and chew on laurel or inhale the smoke of laurel leaves. The smoke of the laurel leaves caused hallucinations and Pythia was ready to communicate with god. The priests were present, although in another room, and were writing down the words of the oracle. All the prophecies were ambiguous or of double meaning; they were the words of the God.
Recent evidence proves that natural gas was evaporating from chasms on the rocks where the temple was situated. This gas was actually the reason of the hallucinations, not the laurel leaves as the history implies. These vapors of the gases resulted in loosening the lips of Pythia and her vague and hardly interpreted omens. Plutarch was the first who had noticed the gases but no one before had ever elaborated on the issue.
Till today, the name Pythia remains synonymous to ambiguity and riddles.