beetling cliffs." Tu Mu's note is "ground covered with trees and
rocks, and intersected by numerous ravines and pitfalls." This
is very vague, but Chia Lin explains it clearly enough as a
defile or narrow pass, and Chang Yu takes much the same view. On
the whole, the weight of the commentators certainly inclines to
the rendering "defile." But the ordinary meaning of the Chinese
in one place is "a crack or fissure" and the fact that the
meaning of the Chinese elsewhere in the sentence indicates
something in the nature of a defile, make me think that Sun Tzu
is here speaking of crevasses.]

should be left with all possible speed and not approached.
16. While we keep away from such places, we should get the
enemy to approach them; while we face them, we should let the
enemy have them on his rear.
17. If in the neighborhood of your camp there should be any
hilly country, ponds surrounded by aquatic grass, hollow basins
filled with reeds, or woods with thick undergrowth, they must be
carefully routed out and searched; for these are places where men
in ambush or insidious spies are likely to be lurking.

[Chang Yu has the note: "We must also be on our guard
against traitors who may lie in close covert, secretly spying out
our weaknesses and overhearing our instructions."]

18. When the enemy is close at hand and remains quiet, he
is relying on the natural strength of his position.

[Here begin Sun Tzu's remarks on the reading of signs, much
of which is so good that it could almost be included in a modern
manual like Gen. Baden-Powell's "Aids to Scouting."]

19. When he keeps aloof and tries to provoke a battle, he
is anxious for the other side to advance.

[Probably because we are in a strong position from which he
wishes to dislodge us. "If he came close up to us, says Tu Mu,
"and tried to force a battle, he would seem to despise us, and
there would be less probability of our responding to the
challenge."]

20. If his place of encampment is easy of access, he is
tendering a bait.
21. Movement amongst the trees of a forest shows that the
enemy is advancing.

[Ts`ao Kung explains this as "felling trees to clear a
passage," and Chang Yu says: "Every man sends out scouts to
climb high places and observe the enemy. If a scout sees that
the trees of a forest are moving and shaking, he may know that
they are being cut down to clear a passage for