The opportunity to secure ourselves against defeat lies in our own hands
Generally in war the best policy is to take a state intact; to ruin it is inferior to this.
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.
Spies are a most important element in water, because on them depends an army's ability to move.
Know thy enemy and know thy self and you will win a hundred battles.
It is through the dispositions of an army that its condition may be discovered. Conceal your dispositions, and your condition will remain secret, which leads to victory,; show your dispositions, and your condition will become patent, which leads to defeat.