If we know that the enemy is open to attack, and also know that our men are in a condition to attack, but are unaware that the nature of the ground makes fighting impracticable, we have still gone only halfway towards victory.
I may take this opportunity of pointing out the rather nice distinction in meaning between 擊 and 攻. The latter is simply “to attack” without any further implication, whereas 擊 is a stronger word which in nine cases out of ten means “to attack with expectation of victory,” “to fall upon,” as we should say, or even “to crush.” On the other hand, 擊 is not quite synonymous with 伐, which is mostly used of operations on a larger scale, as of one State making war on another, often with the added idea of invasion. 征, finally, has special reference to the subjugation of rebels. See Mencius, VII. 2. ii. 2.
30. 故知兵者動而不迷舉而不窮
Hence the experienced soldier, once in motion, is never bewildered; once he has broken camp, he is never at a loss.
The reason being, according to Tu Mu, that he has taken his measures so thoroughly as to ensure victory beforehand. “He does not move recklessly,” says Chang Yü, “so that when he does move, he makes no mistakes.” Another reading substitutes 困 for 迷 and 頓 for 窮. The latter variant only is adopted by the T‘ung Tien and Yü Lan. Note that 窮 here means “at the end of his mental resources.”
31. 故曰知彼知己勝乃不殆知地知天勝乃可全
Hence the saying: If you know the enemy and know yourself, your victory will not stand in doubt;
Capt. Calthrop makes the saying end here, which cannot be justified.
if you know Heaven and know Earth,
天 and 地 are transposed for the sake of the jingle between 天 and 全. The original text, however, has 知天知地, and the correction has been made from the T‘ung Tien.