First learn to become invincible, then wait for your enemy's moment of vulnerability.
In warfare, there are no constant conditions. He who can modify his tactics in relation to his opponent will succeed and win.
Ground which can be abandoned but is hard to re-occupy is called entangling.
Where the army is, prices are high; when prices rise the wealth of the people is exhausted.
In the midst of difficulties we are always ready to seize an advantage, we may extricate ourselves from misfortune.
There is no instance of a nation benefiting from prolonged warfare.