Chang Yü’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. An example of 覆 _fou_^4 in the meaning of “ambuscade” may be found in the _Tso Chuan_, 隱 9th year: 君爲三覆以待之. In the present passage, however, it is to be distinguished from 伏 just above, in that it implies onward motion on the part of the attacking force. Thus, Li Ch‘üan defines it as 不意而至, and Tu Mu as 來襲我也. 23. 塵高而銳者車來也卑而廣者徒來也散而條達者樵採也少而往來者營軍也 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. 高而銳 “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 Yü, “every army on the march must have scouts (探候之人) 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.”[174] When it branches out in different directions, it shows that parties have been sent to collect firewood. There is some doubt about the reading 樵採. The _T‘ung Tien_ and _Yü Lan_ have 薪採, and Li Ch‘üan proposes 薪來. A few clouds of dust moving to and fro signify that the army is encamping. Chang Yü says: “In apportioning the defences 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. 辭卑而益備者進也辭强而進驅者退也 Humble words and increased preparations are signs that the enemy is about to advance.