Know thy enemy and know thy self and you will win a hundred battles.

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.

Do not press an enemy at bay.

Unless you enter the tiger's lair, you cannot get hold of the tiger's cub's.

If we do not wish to fight, we can prevent the enemy from engaging us even though the lines of our encampment be merely traced out on the ground. All we need to do is to throw something odd and unaccountable in his way.

Be subtle! be subtle! and use your spies for every kind of business.

Fighting with a large army under your command is nowise different from fighting with a small one: it is merely a question of instituting signs and signals.