and crevasses,[Defined by Mei Yao-ch`en as "a narrow difficult way between 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 the enemy's march."]
The appearance of a number of screens in the midst of thick grass means that the enemy wants to make us suspicious.
[Tu Yu's explanation, borrowed from Ts`ao Kung's, is as follows: "The presence of a number of screens or sheds in the midst of thick vegetation is a sure sign that the enemy has fled and, fearing pursuit, has constructed these hiding-places in order to make us suspect an ambush." It appears that these "screens" were hastily knotted together out of any long grass which the retreating enemy happened to come across.]
22. The rising of birds in their flight is the sign of an ambuscade.
[Chang Yu's explanation is doubtless right: "When birds that are flying along in a straight line suddenly shoot upwards, it means that soldiers are in ambush at the spot beneath."]
Startled beasts indicate that a sudden attack is coming.
23. When there is dust rising in a high column, it is the sign of chariots advancing; when the dust is low, but spread over a wide area, it betokens the approach of infantry.
["High and sharp," or rising to a peak, is of course somewhat exaggerated as applied to dust. The commentators explain the phenomenon by saying that horses and chariots, being heavier than men, raise more dust, and also follow one another in the same wheel-track, whereas foot-soldiers would be marching in ranks, many abreast. According to Chang Yu, "every army on the march must have scouts some way in advance, who on sighting dust raised by the enemy, will gallop back and report it to the commander-in-chief." Cf. Gen. Baden-Powell: "As you move along, say, in a hostile country, your eyes should be looking afar for the enemy or any signs of him: figures, dust rising, birds getting up, glitter of arms, etc." [1] ]
When it branches out in different directions, it shows that parties have been sent to collect firewood. A few clouds of dust moving to and fro signify that the army is encamping.
[Chang Yu says: "In apportioning the defenses for a cantonment, light horse will be sent out to survey the position and ascertain the weak and strong points all along its circumference. Hence the small quantity of dust and its motion."]
24. Humble words and increased preparations are signs that the enemy is about to advance.
["As though they stood in great fear of us," says Tu Mu.
"Their object is to make us contemptuous and careless, after which they will attack us." Chang Yu alludes to the story of T`ien Tan of the Ch`i-mo against the Yen forces, led by Ch`i Chieh. In ch. 82 of the SHIH CHI we read: "T`ien Tan openly said: 'My only fear is that the Yen army may cut off the noses of their Ch`i prisoners and place them in the front rank to fight against us; that would be the undoing of our city.' The other side being informed of this speech, at once acted on the suggestion; but those within the city were enraged at seeing their fellow-countrymen thus mutilated, and fearing only lest they should fall into the enemy's hands, were nerved to defend themselves more obstinately than ever. Once again T`ien Tan sent back converted spies who reported these words to the enemy:
"What I dread most is that the men of Yen may dig up the ancestral tombs outside the town, and by inflicting this indignity on our forefathers cause us to become faint-hearted.'
