History of the Peloponnesian War

There was one Cylon, a man who had conquered at the Olympic games, an Athenian of the olden time, both noble and powerful; he had married a daughter of Theagenes, a Megarean, who at that time was tyrant of Megara.

Now when Cylon was consulting the oracle at Delphi, the god told him to seize on the Acropolis of the Athenians during the greatest feast of Jupiter.