Be extremely subtle even to the point of formlessness. Be extremely mysterious even to the point of soundlessness. Thereby you can be the director of the opponent's fate.
The skillful employer of men will employ the wise man, the brave man, the covetous man, and the stupid man.
If you know the enemy and know yourself, you need not fear the results of a hundred battles.
If we know that our own men are in a condition to attack, but are unaware that the enemy is not open to attack, we have gone only halfway towards victory.