History of the Peloponnesian War

Accordingly, procuring a force from Theagenes and persuading his friends to join him, when the Olympic festival in Peloponnese came, he seized the Acropolis, with the intention of making himself tyrant, thinking that this was the grand festival of Zeus, and also an occasion appropriate for a victor at the Olympic games.

Whether the grand festival that was meant was in Attica or elsewhere was a question which he never thought of, and which the oracle did not offer to solve. For the Athenians also have a festival which is called the grand festival of Zeus Meilichios or Gracious, viz. the Diasia. It is celebrated outside the city, and the whole people sacrifice not real victims but a number of bloodless offerings peculiar to the country. However, fancying he had chosen the right time, he made the attempt.