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.

He sent to Astyochus, the Lacedaemonian admiral, who was at this time still in the neighbourhood of Miletus, secret information by letter that Alcibiades was ruining the Lacedaemonian cause by making Tissaphernes a friend of the Athenians, and also wrote an explicit account of his other doings; he added that it was pardonable in himself to devise evil for an enemy, even though this involved detriment to his state.[*](cf. 6.92.2 for similar excuse.)