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.
" Perhaps some of us are emboldened by our superiority in arms and numbers, which enables us freely to invade and lay waste their territory.
But there is other territory in plenty over which they hold sway, and they will import by sea whatever they need.
And if, on the other hand, we try to induce their allies to revolt, we shall have in addition to protect them with a fleet, since they are chiefly islanders.
What then will be the character of the war we shall be waging? Unless we can either win the mastery on the sea or cut off the revenues by which they support their navy, we shall get the worst of it.