Mei Yao-ch‘ên has rather an interesting note: # "Knowledge of the spirit-world is to be obtained by divination; information in natural science may be sought by inductive reasoning; the laws of the universe can be verified by mathematical calculation: but the dispositions of an enemy are ascertainable through spies and spies alone."
In the enemy's country, win people over by kind treatment, and use them as spies."
"We ostentatiously do things calculated to deceive out own spies, who must be led to believe that they have been unwittingly disclosed. Then, when these spies are captured in the enemy's lines, they will make an entirely false report, and the enemy will take measures accordingly, only to find that we do something quite different. The spies will thereupon be put to death."
The whole secret lies in confusing the enemy/
the people
, so that he cannot fathom our real intent.'" To put it perhaps a little more clearly: any attack or other operation is CHENG, on which the enemy/
the people
has had his attention fixed; whereas that is CH`I," which takes him by surprise or comes from an unexpected quarter. If the enemy/
the people
perceives a movement which is meant to be CH`I," it immediately becomes CHENG."