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.

for to those who have never given them aid according to the terms of their alliance they of their own accord have fulfilled an ally's obligations with a zeal exceeding their compact. That the Athenians entertain these designs of aggrandisement is quite pardonable;

and I have no word of blame for those who wish to rule, but only for those who are too ready to submit; for it is an instinct of man's nature always to rule those who yield, but to guard against those who are ready to attack.