19. 故能而示之不能用而示之不用近而示之遠遠而示之近
Hence, when able to attack, we must seem unable; when using our forces, we must seem inactive; when we are near, we must make the enemy believe we are far away; when far away, we must make him believe we are near.
20. 利而誘之亂而取之
Hold out baits to entice the enemy. Feign disorder, and crush him.
取, as often in Sun Tzŭ, is used in the sense of 擊. It is rather remarkable that all the commentators, with the exception of Chang Yü, refer 亂 to the enemy: “when he is in disorder, crush him.” It is more natural to suppose that Sun Tzŭ is still illustrating the uses of deception in war.
21. 實而備之强而避之
If he is secure at all points, be prepared for him. If he is in superior strength, evade him.
The meaning of 實 is made clear from [chap. VI], where it is opposed to 虛 “weak or vulnerable spots.” 强, according to Tu Yu and other commentators, has reference to the keenness of the men as well as to numerical superiority. Capt. Calthrop evolves an extraordinarily far-fetched translation: “If there are defects, give an appearance of perfection, and awe the enemy. Pretend to be strong, and so cause the enemy to avoid you”!
22. 怒而撓之卑而驕之
If your opponent is of choleric temper, seek to irritate him. Pretend to be weak, that he may grow arrogant.