History of the Peloponnesian War
Thucydides
Thucydides, Vol. 1-4. Smith, Charles Foster, translator. London and Cambridge, MA: Heinemann and Harvard University Press, 1919-1923.
And first the Lacedaemonian envoys bade the Athenians drive out the "curse of the goddess." The curse was as follows:
There was an Athenian in days of old named Cylon, a victor at Olympia, of noble birth and powerful; and he had married a daughter of Theagenes, a Megarian, who was at that time tyrant of Megara.
Now Cylon consulted the oracle at Delphi, and the god in answer told him to seize the Acropolis of Athens "at the greatest festival of Zeus."
So he obtained a force from Theagenes and, persuading his friends to help, when the Olympic festival in the Peloponnesus came on he seized the Acropolis with a view to making himself tyrant; for he thought that the Olympic festival was not only the greatest festival of Zeus, but also in a manner was connected with him as having won an Olympic victory.[*](On this first attempt to establish a tyranny in Athens, see also Hdt. 5.71; Plut. Sol. 12. It was not a rising of the people against the nobles, but the attempt of an ambitious man who aspired to royal power, supported only by a few friends and a body of Megarian soldiers. To the mass of the people it seemed to portend subjection to Megara, so they flocked in to crush the movement, not, as Cylon hoped, to support it.)
But whether the oracle meant the greatest festival in Attica or somewhere else he did not go on to consider, and the oracle did not make it clear. For, in fact, the Athenians also have a festival in honour of Zeus Meilichius, the Diasia, as it is called, a very great festival celebrated outside the city, whereat all the people offer sacrifices, many making offerings[*](A scholiast suggests cakes (πέμματα) made in the forms of animals.) peculiar to the country instead of victims. But Cylon, thinking that he was right in his opinion, made his attempt.
And the Athenians, when they were aware of it, came in a body from the fields against them and sitting down before the Acropolis laid siege to it.
But as time passed the Athenians grew weary of the siege and most of them went away, committing the task of guarding to the nine Archons, to whom they also gave full power to settle the whole matter as they might determine to be best;