Spies cannot be usefully employed without a certain intuitive sagacity; (2) They cannot be properly managed without benevolence and straight forwardness; (3) Without subtle ingenuity of mind, one cannot make certain of the truth of their reports; (4) Be subtle! be subtle! and use your spies for every kind of warfare; (5) 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.