發其機, literally, “releases the spring” (see V. § 15), that is, takes some decisive step which makes it impossible for the army to return—like 項羽 Hsiang Yü, who sunk his ships after crossing a river. Ch‘ên Hao, followed by Chia Lin, understands the words less well as 發其心機 “puts forth every artifice at his command.” But 機 in this derived sense occurs nowhere else in Sun Tzŭ. 39. 焚舟破釜若驅羣羊而往驅而來莫知所之 He burns his boats and breaks his cooking-pots; Omitted in the _T‘u Shu_. like a shepherd driving a flock of sheep, he drives his men this way and that, and none knows whither he is going. The _T‘u Shu_ inserts another 驅 after 羊. Tu Mu says: 三軍但知進 退之命不知攻取之端也 “The army is only cognisant of orders to advance or retreat; it is ignorant of the ulterior ends of attacking and conquering.” 40. 聚三軍之衆投之於險此謂將軍之事也 To muster his host and bring it into danger:—this may be termed the business of the general. Sun Tzŭ means that after mobilisation there should be no delay in aiming a blow at the enemy’s heart. With 投之於險 cf. _supra_, § 23: 投之無所往. Note how he returns again and again to this point. Among the warring states of ancient China, desertion was no doubt a much more present fear and serious evil than it is in the armies of to-day. 41. 九地之變屈伸之利人情之理不可不察也 The different measures suited to the nine varieties of ground; Chang Yü says: 九地之法不可拘泥 “One must not be hide-bound in interpreting the rules for the nine varieties of ground. the expediency of aggressive or defensive tactics; The use of 屈伸 “contraction and expansion” may be illustrated by the saying 屈以求伸, which almost exactly corresponds to the French “il faut reculer pour mieux sauter.”[182] Capt. Calthrop, _more suo_, avoids a real translation and has: “the suiting of the means to the occasion.” and the fundamental laws of human nature: these are things that must most certainly be studied. 42. 凡爲客之道深則專淺則散 When invading hostile territory, the general principle is, that penetrating deeply brings cohesion; penetrating but a short way means dispersion. Cf. _supra_, § 20. 43. 去國越境而師者絶地也四達者衢地也 When you leave your own country behind, and take your army across neighbouring territory, Chang Yü’s paraphrase is 而用師者. you find yourself on critical ground.