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 in that case we should be guilty of impiety if we changed our friends, nor should we find others more congenial.

In view of these things, be well advised, and make it your endeavour that the Peloponnesian league shall be no weaker under your leadership than when you inherited it from your fathers."