Chapter 13: The Use of Spies

XIII. THE USE OF SPIES

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.

[Cf. II. ss. ss. 1, 13, 14.]

There will be commotion at home and abroad, and men will drop
down exhausted on the highways.

[Cf. TAO TE CHING, ch. 30: "Where troops have been
quartered, brambles and thorns spring up. Chang Yu has the note:
"We may be reminded of the saying: 'On serious ground, gather in
plunder.' Why then should carriage and transportation cause
exhaustion on the highways?--The answer is, that not victuals
alone, but all sorts of munitions of war have to be conveyed to
the army. Besides, the injunction to 'forage on the enemy' only
means that when an army is deeply engaged in hostile territory,
scarcity of food must be provided against. Hence, without being
solely dependent on the enemy for corn, we must forage in order
that there may be an uninterrupted flow of supplies. Then,
again, there are places like salt deserts where provisions being
unobtainable, supplies from home cannot be dispensed with."]

As many as seven hundred thousand families will be impeded in
their labor.

[Mei Yao-ch'en says: "Men will be lacking at the plough-
tail." The allusion is to the system of dividing land into nine
parts, each consisting of about 15 acres, the plot in the center
being cultivated on behalf of the State by the tenants of the
other eight. It was here also, so Tu Mu tells us, that their
cottages were built and a well sunk, to be used by all in common.
[See II. ss. 12, note.] In time of war, one of the families had
to serve in the army, while the other seven contributed to its
support. Thus, by a levy of 100,000 men (reckoning one able-
bodied soldier to each family) the husbandry of 700,000 families
would be affected.]

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,

["For spies" is of course the meaning, though it would spoil
the effect of this curiously elaborate exordium if spies were
actually mentioned at this point.]

is the height of inhumanity.

[Sun Tzu's agreement is certainly ingenious. He begins by
adverting to the frightful misery and vast expenditure of blood
and treasure which war always brings in its train. Now, unless
you are kept informed of the enemy's condition, and are ready to
strike at the right moment, a war may drag on for