In the ancient times the “Oracle of Delphi” was considered as the centre of the earth. It was also the most imperative shrine in ancient Greece. A home to “Pythia”, mouthpiece of Apollo answered to the pilgrimage that came to her doorsteps. Pythia was a role filled by different women who acted as a medium through which Apollo spoke. Her answers determined when the farmers can plant their crops and when can an empire declare war.
According to the legend, Pythia was in a frantic state engendered by the vapours, rising from the chasm in the rock beneath her.
Later the studies revealed the gases rising from the fissure of the rock were natural gases, and it induced a thrilling and stimulating effect on Pythia who inhaled it.
(source: https://news.nationalgeographic.co.in)