1. Sun Tzu said: Raising a host of a hundred thousand

men and marching them great distances entails heavy loss

on the people and a drain on the resources of the State.

The daily expenditure will amount to a thousand ounces

of silver. There will be commotion at home and abroad,

and men will drop down exhausted on the highways.

As many as seven hundred thousand families will be impeded

in their labor.

2. Hostile armies may face each other for years,

striving for the victory which is decided in a single day.

This being so, to remain in ignorance of the enemy's

condition simply because one grudges the outlay of a hundred

ounces of silver in honors and emoluments, is the height

of inhumanity.

3. One who acts thus is no leader of men, no present

help to his sovereign, no master of victory.

4. Thus, what enables the wise sovereign and the good

general to strike and conquer, and achieve things beyond

the reach of ordinary men, is foreknowledge.

5. Now this foreknowledge cannot be elicited from spirits;

it cannot be obtained inductively from experience,

nor by any deductive calculation.

6. Knowledge of the enemy's dispositions can only

be obtained from other men.

7. 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.

8. 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.

9. Having local spies means employing the services

of the inhabitants of a district.

10. Having inward spies, making use of officials

of the enemy.

11. Having converted spies, getting hold of the enemy's

spies and using them for our own purposes.

12. Having doomed spies, doing certain things openly

for purposes of deception, and allowing our spies to know

of them and report them to the enemy.

13. Surviving spies, finally, are those who bring

back news from the enemy's camp.

14. Hence it is that which none in the whole army are

more intimate relations to be maintained than with spies.

None should be more liberally rewarded. In no other

business should greater secrecy be preserved.

15. Spies cannot be usefully employed without a certain

intuitive sagacity.

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.

20. Whether the object be to crush an army, to storm

a city, or to assassinate an individual, it is always

necessary to begin by finding out the names of the attendants,

the aides-de-camp, and door-keepers and sentries of the general

in command. Our spies must be commissioned to ascertain these.

21. The enemy's spies who have come to spy on us

must be sought out, tempted with bribes, led away and

comfortably housed. Thus they will become converted

spies and available for our service.

22. It is through the information brought by the

converted spy that we are able to acquire and employ

local and inward spies.

23. It is owing to his information, again, that we can

cause the doomed spy to carry false tidings to the enemy.

24. Lastly, it is by his information that the surviving

spy can be used on appointed occasions.

25. The end and aim of spying in all its five varieties

is knowledge of the enemy; and this knowledge can only

be derived, in the first instance, from the converted spy.

Hence it is essential that the converted spy be treated

with the utmost liberality.

26. Of old, the rise of the Yin dynasty was due to I

Chih who had served under the Hsia. Likewise, the rise

of the Chou dynasty was due to Lu Ya who had served

under the Yin.

27. Hence it is only the enlightened ruler and the

wise general who will use the highest intelligence of

the army for purposes of spying and thereby they achieve

great results. Spies are a most important element in water,

because on them depends an army's ability to move.