Whether to concentrate or to divide your troops, must be decided by circumstances. 17. 故其疾如風其徐如林 Let your rapidity be that of the wind, The simile is doubly appropriate, because the wind is not only swift but, as Mei Yao-ch‘ên points out, 無形跡 “invisible and leaves no tracks.” your compactness that of the forest. It is hardly possible to take 徐 here in its ordinary sense of “sedate,” as Tu Yu tries to do. Mêng Shih comes nearer the mark in his note 緩行須有行列 “When slowly marching, order and ranks must be preserved”—so as to guard against surprise attacks. But natural forests do not grow in rows, whereas they do generally possess the quality of density or compactness. I think then that Mei Yao-ch‘ên uses the right adjective in saying 如林之森然. 18. 侵掠如火不動如山 In raiding and plundering be like fire, Cf. _Shih Ching_, IV. 3. iv. 6: 如火烈烈則莫我敢曷 “Fierce as a blazing fire which no man can check.” in immovability like a mountain. That is, when holding a position from which the enemy is trying to dislodge you, or perhaps, as Tu Yu says, when he is trying to entice you into a trap. 19. 難知如陰動如雷霆 Let your plans be dark and impenetrable as night, and when you move, fall like a thunderbolt. The original text has 震 instead of 霆. Cf. IV. § 7. Tu Yu quotes a saying of T‘ai Kung which has passed into a proverb: 疾雷不及掩耳疾電不及瞑目 “You cannot shut your ears to the thunder or your eyes to the lightning—so rapid are they.” Likewise, an attack should be made so quickly that it cannot be parried. 20. 掠鄉分衆廓地分利 When you plunder a countryside, let the spoil be divided amongst your men; The reading of Tu Yu, Chia Lin, and apparently Ts‘ao Kung, is 指向分衆, which is explained as referring to the subdivision of the army, mentioned in V. §§ 1, 2, by means of banners and flags, serving to point out (指) to each man the way he should go (向). But this is very forced, and the ellipsis is too great, even for Sun Tzŭ. Luckily, the _T‘ung Tien_ and _Yü Lan_ have the variant 嚮, which not only suggests the true reading 鄉, but affords some clue to the way in which the corruption arose. Some early commentator having inserted 向 as the sound of 鄉, the two may afterwards have been read as one character; and this being interchangeable with 向, 鄉 must finally have disappeared altogether. Meanwhile, 掠 would have been altered to 指 in order to make sense. As regards 分衆, I believe that Ho Shih alone has grasped the real meaning, the other commentators understanding it as “dividing the men into parties” to search for plunder. Sun Tzŭ wishes to lessen the abuses of indiscriminate plundering by insisting that all booty shall be thrown into a common stock, which may afterwards be fairly divided amongst all. when you capture new territory, cut it up into allotments for the benefit of the soldiery.