Chang Yü, following Tu Yu, says: 燒之必退退而逆擊之必死戰則不便也 “When you make a fire, the enemy will retreat away from it; if you oppose his retreat and attack him then, he will fight desperately, which will not conduce to your success.” A rather more obvious explanation is given by Tu Mu: “If the wind is in the east, begin burning to the east of the enemy, and follow up the attack yourself from that side. If you start the fire on the east side, and then attack from the west, you will suffer in the same way as your enemy.” 11. 晝風久夜風止 A wind that rises in the daytime lasts long, but a night breeze soon falls. Cf. Lao Tzŭ’s saying: 飄風不終朝 “A violent wind does not last the space of a morning.” (_Tao Tê Ching_, chap. 23.) Mei Yao-ch‘ên and Wang Hsi say: “A day breeze dies down at nightfall, and a night breeze at daybreak. This is what happens as a general rule.” The phenomenon observed may be correct enough, but how this sense is to be obtained is not apparent. 12. 凡軍必知有五火之變以數守之 In every army, the five developments connected with fire must be known, the movements of the stars calculated, and a watch kept for the proper days. Tu Mu’s commentary shows what has to be supplied in order to make sense out of 以數守之. He says: 須筭星𨇠之數守風起之日乃可發火 “We must make calculations as to the paths of the stars, and watch for the days on which wind will rise, before making our attack with fire.” Chang Yü seems to take 守 in the sense of 防: “We must not only know how to assail our opponents with fire, but also be on our guard against similar attacks from them.” 13. 故以火佐攻者明以水佐攻者强 Hence those who use fire as an aid to the attack show intelligence; I have not the least hesitation in rejecting the commentators’ explanation of 明 as = 明白. Thus Chang Yü says: 灼然可以取勝 “... will _clearly_ [i.e. obviously] be able to gain the victory.” This is not only clumsy in itself, but does not balance 强 in the next clause. For 明 “intelligent,” cf. _infra_, § 16, and _Lun Yü_ XII. 6. those who use water as an aid to the attack gain an accession of strength. Capt. Calthrop gives an extraordinary rendering of the paragraph: “... if the attack is to be assisted, the fire must be unquenchable. If water is to assist the attack, the flood must be overwhelming.” 14. 水可以絶不可以奪 By means of water, an enemy may be intercepted, but not robbed of all his belongings.