16. They cannot be properly managed without benevolence and straightforwardness.
17. Without subtle ingenuity of mind, one cannot make certain of the truth of their reports.
18. Be subtle! be subtle! and use your spies for every kind of business.
19. If a secret piece of news is divulged by a spy before the time is ripe, he must be put to death together with the man to whom the secret was told.