A clever general... avoids an army when its spirit is keen, but attacks it when it is sluggish and inclined to return. This is the art of studying moods. Disciplined and calm, he awaits the appearance of disorder and hubbub among the enemy. This is the art of retaining self-possession.

Energy may be likened to the bending of a crossbow; decision, to the releasing of a trigger.

If you are strong, appear weak. But if you are weak, appear strong.

Move not unless you see an advantage; use not your troops unless there is something to be gained; fight not unless the position is critical.

Bring war material with you from home, but forage on the enemy... use the conquered foe to augment one's own strength.

It is said that if you know your enemies and know yourself, you will not be imperiled in a hundred battles; if you do not know your enemies but do know yourself, you will win one and lose one; if you do not know your enemies nor yourself, you will be imperiled in every single battle.

So a military force has no constant formation, water has no constant shape: the ability to gain victory by changing and adapting according to the opponent is called genius.