Keep your friends close and your enemies even closer.
Attack the enemy's strategy.
He will win who knows how to handle both superior and inferior forces.
Generally in war the best policy is to take a state intact; to ruin it is inferior to this.
He who is not sage and wise, humane and just, cannot use secret agent.s. And he who is not delicate and subtle cannot get the truth out of them.
Knowledge of the enemy's dispositions can only be obtained from other men.