History of the Peloponnesian War

In the enemy's country indeed men ought always to march with boldness of feeling, but at the same time to make their actual preparations with a degree of fear; for in this way they would be at once most full of courage for attacking their adversaries, and most secure against being attacked.

But in our own case, we are not going against a state that is so powerless to defend itself, but against one most excellently provided with every thing; so that we must fully expect that they will meet us in battle; and if they have not already set out before we are there, yet [that they will do so], when they see us in their territory wasting and destroying their property.

For all are angry, when suffering any unwonted evil, to see it done before their eyes, and in their very presence: and those who [on such provocation] reflect the least, set to work with the greatest passion [to avenge themselves].