The sovereign must have full knowledge of the activities of the five sorts of agents. This knowledge must come from the double agents, and therefore it is mandatory that they be treated with the utmost liberality.

The good fighter is able to secure himself against defeat, but cannot make certain of defeating the enemy.

He who relies solely on warlike measures shall be exterminated; he who relies solely on peaceful measures shall perish.

When your opponent gives you an opening, be swift as a hare.

Hostile armies may face each other for years, striving for the victory which is decided in a single day. This being so, to remain in ignorance of the enemy's condition simply because one grudges the outlay of a hundred ounces of silver in honors and emoluments, is the height of inhumanity.

The natural formation of the country is the soldier's best ally

When you surround an army, leave an outlet free. Do not press a desperate foe too hard.