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.
The god answered them, as it is said, that if they warred with all their might, victory would be theirs, and said that he himself would help them, whether invoked or uninvoked.