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 Syracusans, on the other hand, began at once to sail fearlessly about the harbour and determined to close up the entrance to it, in order that the Athenians might no longer be able, even if they wished, to sail out unobserved.