Six Secret Teachings, Tiger Teaching — Empty Ramparts六韜 壘虛
1Knowing whether the enemy's ramparts are empty or full — birds that take no fright mean straw men
武王問太公曰:「何以知敵壘之虛實,自來自去?」太公曰:「將必上知天道,下知地利,中知人事。登高下望,以觀敵之變動。望其壘,則知其虛實;望其士卒,則知其來去。」武王曰:「何以知之?」太公曰:「聽其鼓無音,鐸無聲,望其壘上多飛鳥而不驚,上無氛氣,必知敵詐而為偶人也。敵人猝去不遠,未定而復反者,彼用其士卒太疾也。太疾則前後不相次,不相次則行陣必亂。如此者,急出兵擊之。以少擊眾,則必敗矣。」
King Wu asked Taigong, "By what means do we know whether the enemy's ramparts are empty or full, and whether he comes or goes?" Taigong said, "A general must know the way of Heaven above, the advantage of the ground below, and the affairs of men between. Climb high and look down, and watch how the enemy moves and changes. Look at his ramparts, and you know whether they are empty or full; look at his officers and men, and you know whether they come or go." King Wu said, "How is it known?" Taigong said, "When you hear no note from his drums and no sound from his bells, and see many birds flying over his ramparts and taking no fright, and no haze of vapor above them, then you know for certain that the enemy has played you false and set up straw men. When the enemy goes off all at once, does not go far, and turns back again before he has settled, he is using his officers and men too fast. Too fast, and front and rear do not keep their order; and without order his ranks are sure to fall into confusion. Strike at once, and though you be few and they many, the enemy is sure to be beaten."