13. The Use of Spies
Tu Mu and Mei Yao-ch`en point out that the spy is privileged to enter even the general's private sleeping-tent.
None should be more liberally rewarded. In no other business should greater secrecy be preserved.
Tu Mu gives a graphic touch: all communication with spies should be carried "mouth-to-ear." The following remarks on spies may be quoted from Turenne, who made perhaps larger use of them than any previous commander: "Spies are attached to those who give them most, he who pays them ill is never served. They should never be known to anybody; nor should they know one another. When they propose anything very material, secure their persons, or have in your possession their wives and children as hostages for their fidelity. Never communicate anything to them but what is absolutely necessary that they should know.[2="Marshal Turenne," p. 311.]