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.

Hence the saying: If you know the enemy and you know yourself your victory will not stand in doubt, if you now Heaven and you know Earth you may make your victory complete.