The sovereign must have full knowledge of the activities of the five sorts of agents. This knowledge must come from the double agents, and therefore it is mandatory that they be treated with the utmost liberality.

the leader of armies is the arbiter of the people's fate, the man on whom it depends whether the nation shall be in peace or in peril.

If soldiers are punished before they have grown attached to you, they will not prove submissive; and, unless submissive, then will be practically useless. If, when the soldiers have become attached to you, punishments are not enforced, they will still be unless.

Correct your mistake as soon as you have found it.

In war, then, let your great object be victory, not lengthy campaigns.

One who has few must prepare against the enemy; one who has many makes the enemy prepare against him.

It is only one who is thoroughly acquainted with the evils of war that can thoroughly understand the profitable way of carrying it on.