Delphi under towering Parnassus, where Apollo's oracle was,
plays an important part in mythology. Castalia was its
sacred spring; Cephissus its river. It was held to be the
center of the world, so many pilgrims came to it, from
foreign countries as well as Greece. No other shrine rivaled
it. The answers to the questions asked by the anxious
seekers for Truth were delivered by a priestess who went into
a trance before she spoke.
[ Mythology, by Edith Hamilton ]