Thucydides Quote

Disdain is the privilege of those who, like us, have been assured by reflection of their superiority to their adversary. And where the chances are the same, knowledge fortifies courage by the contempt which is its consequence, its trust being placed, not in hope, which is the prop of the desperate, but in a judgment grounded upon existing resources, whose anticipations are more to be depended upon.

Book II, 2.62-- - History of the Peloponnesian War