He who wishes to fight must first count the cost. When you engage in actual fighting, if victory is long in coming, then men's weapons will grow dull and their ardor will be dampened. If you lay siege to a town, you will exhaust your strength.

It is ten thousand times cheaper to pay the best spies lavishly than even a tiny army poorly.

In the midst of difficulties we are always ready to seize an advantage, we may extricate ourselves from misfortune.

If your enemy is secure at all points, be prepared for him. If he is in superior strength, evade him. If your opponent is tempermental, seek to irritate him. Pretend to be weak, that he may grow arrogant. If he is taking his ease, give him no rest. If his forces are united, separate them. If sovereign and subject are in accord, put division between them. Attack him where he is unprepared, appear where you are not expected.

If ignorant both of your enemy and yourself, you are certain to be in peril.

Agitate him and ascertain the pattern of his movement.

What is of the greatest importance in war is extraordinary speed: One cannot afford to neglect opportunity.