by mathematical calculation: but the dispositions of an enemy are ascertainable through spies and spies alone."]
- Hence the use of spies, of whom there are five classes: (1) Local spies; (2) inward spies; (3) converted spies; (4) doomed spies; (5) surviving spies.
- When these five kinds of spy are all at work, none can discover the secret system. This is called "divine manipulation of the threads." It is the sovereign’s most precious faculty.
[Cromwell, one of the greatest and most practical of all cavalry leaders, had officers styled ‘scout masters,’ whose business it was to collect all possible information regarding the enemy, through scouts and spies, etc., and much of his success in war was traceable to the previous knowledge of the enemy’s moves thus gained." [1] ]
- Having local spies means employing the services of the inhabitants of a district.
[Tu Mu says: "In the enemy’s country, win people over by kind treatment, and use them as spies."]
- Having inward spies, making use of officials of the enemy.
[Tu Mu enumerates the following classes as likely to do good service in this respect: "Worthy men who have been degraded from office, criminals who have undergone punishment; also, favourite concubines who are greedy for gold, men who are aggrieved at being in subordinate positions, or who have been passed over in the distribution of posts, others who are anxious that their side should be defeated in order that they may have a chance of displaying their ability and talents, fickle turncoats who always want to have a foot in each boat. Officials of these several kinds," he continues, "should be secretly approached and bound to one’s interests