History of the Peloponnesian War

You ought likewise to fortify Deceleia in the territory of Athens, a thing which the Athenians themselves most fear, and reckon for the only evil they have not yet tasted in this war.

And the way to hurt an enemy most is to know certainly what he most feareth and to bring the same upon him. For in reason a man therefore feareth a thing most as having the precisest knowledge of what will most hurt him. As for the commodities which yourselves shall reap and deprive the enemy of by so fortifying, letting much pass, I will sum you up the principal. Whatsoever the territory is furnished withal will come most of it unto you, partly taken and partly of its own accord.