The Oracle of Delphi, known through-out the ancient world, occupied a site beneath the towering cliffs called the Phaidriades in an imposing ravine on the side of Mt Parnassus. The site was dedicated to Apollo, god of moderation and of music, whose job it was to ensure that sacred laws of Zeus were kept. For the ancients, Delphi was the centre of the world, the so-called omphalos or navel of the earth. Before the cult of Apollo was established, the oracle belonged to the earth-goddess Gaea and it was guarded by a dragon called Python, whom Apollo had to slay before Delphi could become his. At a very early date, the Delphic Oracle gained a worldwide reputation. The dininations of the Pythia, priestess of Apollo, played a central part in the lives not only of ordinary people but also of the cities and states of Antiquity, and influenced the important or even historic decisions they took. To begin with, oracles were given only on the seventh day of the ancient month Bysius; later, they could be obtained one day a month – with the exception of the three winter months, for Apollo was absent then, in the northern land of the Hyperboreans, and Dionysus guarded the sanctuary in his stead. Before a question could be put to the oracle, the petitioner had to pay a special tax, purify himself and make sacrifices. The Pythia and her assistant priestess washed at the Castallian spring , near the sanctuary, and then descended into the depths of the temple. The Pythia, seated on a copper trpod over a crevice in the ground, chewed laurel leaves and inhaled the vapours emerging from the earth. The god then spoke through her mouth, in a language which only the priests of the sanctuary could understand and interpret. His answers were often indefinite and ambiguous, but that in no way reduced popular respect for the wisdom of his judgement.