[Ts’ao Kung’s note is "Make a display of weakness and want." Tu Mu says: "If our force happens to be superior to the enemy’s, weakness may be simulated in order to lure him on; but if inferior, he must be led to believe that we are strong, in order that he may keep off. In fact, all the enemy’s movements should be determined by the signs that we choose to give him." Note the following anecdote of Sun Pin, a descendent of Sun Wu: In 341 B.C., the Ch’i State being at war with Wei, sent T’ien Chi and Sun Pin against the general P’ang Chuan, who happened to be a deadly personal enemy of the later. Sun Pin said: "The Ch’i State has a reputation for cowardice, and therefore our adversary despises us. Let us turn this circumstance to account." Accordingly, when the army had crossed the border into Wei territory, he gave orders to show 100,000 fires on the first night, 50,000 on the next, and the night after only 20,000. P’ang Chuan pursued them hotly, saying to himself: "I knew these men of Ch’i were cowards: their numbers have already fallen away by more than half." In his retreat, Sun Pin came to a narrow defile, which he calculated that his pursuers would reach after dark. Here he had a tree stripped of its bark, and inscribed upon it the words: "Under this tree shall P’ang Chuan die." Then, as night began to fall, he placed a strong body of archers in ambush near by, with orders to shoot directly if they saw a light. Later on, P’ang Chuan arrived at the spot, and noticing the tree, struck a light in order to read what was written on it. His body was immediately riddled by a volley of arrows, and his whole army thrown into confusion. [The above is Tu Mu’s version of the story; the _Shih Chi_, less dramatically but probably with more historical truth, makes P’ang Chuan cut his own throat with an exclamation of despair, after the rout of his army.] ] He sacrifices something, that the enemy may snatch at it. 20. By holding out baits, he keeps him on the march; then with a body of picked men he lies in wait for him. [With an emendation suggested by Li Ching, this then reads, "He lies in wait with the main body of his troops."] 21. The clever combatant looks to the effect of combined energy, and does not require too much from individuals. [Tu Mu says: "He first of all considers the power of his army in the bulk; afterwards he takes individual talent into account, and uses each men according to his capabilities. He does not demand perfection from the untalented."] Hence his ability to pick out the right men and utilise combined energy. 22. When he utilises combined energy, his fighting men become as it were like unto rolling logs or stones. For it is the nature of a log or stone to remain motionless on level ground, and to move when on a slope; if four-cornered, to come to a standstill, but if round-shaped, to go rolling down. [Ts’au Kung calls this "the use of natural or inherent power."]