13. 故形人而我無形則我專而敵分
By discovering the enemy’s dispositions and remaining invisible ourselves, we can keep our forces concentrated, while the enemy’s must be divided.
The conclusion is perhaps not very obvious, but Chang Yü (after Mei Yao-ch‘ên) rightly explains it thus: “If the enemy’s dispositions are visible, we can make for him in one body; whereas, our own dispositions being kept secret, the enemy will be obliged to divide his forces in order to guard against attack from every quarter.” 形 is here used as an active verb: “to make to appear.” See IV, note on heading. Capt. Calthrop’s “making feints” is quite wrong.
14. 我專爲一敵分爲十是以十共其一也則我衆而敵寡
We can form a single united body, while the enemy must split up into fractions. Hence there will be a whole pitted against separate parts of a whole,
The original text has 以敵攻其一也, which in accordance with the T‘ung Tien and Yü Lan has been altered as above. I adopt the more plausible reading of the T‘u Shu: 是以十攻其一也, in spite of having to refer 十 to ourselves and not to the enemy. Thus Tu Yu and Mei Yao-ch‘ên both regard 十 as the undivided force, consisting of so many parts, and 一 as each of the isolated fractions of the enemy. The alteration of 攻 into 共 can hardly be right, though the true text might conceivably have been 是以十共攻其一也.
which means that we shall be many to the enemy’s few.
15. 能以衆擊寡者則吾之所與戰者約矣
And if we are able thus to attack an inferior force with a superior one, our opponents will be in dire straits.
For 擊, the T‘ung Tien and Yü Lan have 敵. Tu Yu, followed by the other commentators, arbitrarily defines 約 as 少而易勝 “few and easy to conquer,” but only succeeds thereby in making the sentence absolutely pointless. As for Capt. Calthrop’s translation: “In superiority of numbers there is economy of strength,” its meaning is probably known to himself alone. In justification of my own rendering of 約, I would refer to Lun Yü IV. 2 and VII. 25 (3).