History of the Peloponnesian War
Thucydides
Thucydides. History of the Peloponnesian War. Crawley, Richard, translator. London and Toronto: J. M. Dent and Sons Ltd.; New York: E. P. Dutton and Co., 1914.
Next, when the barbarian invaded Hellas, they say that they were the only Boeotians who did not Medise; and this is where they most glorify themselves and abuse us.
We say that if they did not Medise, it was because the Athenians did not do so either; just as afterwards when the Athenians attacked the Hellenes they, the Plataeans, were again the only Boeotians who Atticized.