The supreme art of war is to subdue the enemy without fighting.
If the enemy opens the door, you must race in.
What enables the wise sovereign and the good general to strike and conquer, and achieve things beyond the reach of ordinary men, is foreknowledge.
There is no instance of a nation benefiting from prolonged warfare.
Of old the expert in battle would first make himself invincible and then wait for his enemy to expose his vulnerability.
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.