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
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
6. Knowledge of the enemy's dispositions can only be obtained from
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
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
15. Spies cannot be usefully employed without a certain intuitive
16. They cannot be properly managed without benevolence and
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
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
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.