Delphic oracle

The Pythia (Greek: Πυθία [pyːˈtʰi.a]), commonly known as the Oracle of Delphi, was the priestess at the Temple of Apollo at Delphi, located on the slopes of Mount Parnassus. The Pythia was widely credited for her prophecies inspired by Apollo. The Delphic oracle was established in the 8th century BCE. The last recorded response was given during AD 393, when the emperor Theodosius I ordered pagan temples to cease operation.

Select Prophicies
In 480 BC, when Xerxes, the son of Darius the Great of Persia, returned to finish the job of conquering the Greeks in which his father had failed, the Athenians consulted the oracle. They were told:
 * "Now your statues are standing and pouring sweat. They shiver with dread. The black blood drips from the highest rooftops. They have seen the necessity of evil. Get out, get out of my sanctum and drown your spirits in woe."

It was unambiguous. When persuaded to seek advice a second time, the oracle gave a way for the Athenians to escape their doom. When Athena approached her father to help her city, Zeus responded that he would grant that "a wall of wood alone shall be uncaptured, a boon to you and your children."

Back in Athens Themistocles argued that the wall of wood referred to the Athenian navy and persuaded the Athenians to pursue their policy of using wealth from their Attic silver mines at Laurium to continue building their fleet. On the grounds that the oracle referred to the nearby island of Salamis as "holy", he claimed that those slain would be Greece's enemies, not the Athenians. For these the oracle would have said "O cruel Salamis". His voice carried the day, Athens was evacuated to Salamis and in a following naval battle the Athenian fleet and its allies destroyed the Persian fleet at Salamis, while watched by Xerxes. Despite the fact that Athens was burned by the Persians, her occupants were saved, the Persian risk was ended and the authority of the Oracle was never higher.

Delphic oracle in "Counting Potsherds"
With the threat of renewed Persian invasion led by Khsrish I (later "The Conqueror"), the Athenians consulted the Delphic oracle.