Ts‘ao Kung says that the 五利 are 下五事也 “the five things that follow;” but this cannot be right. We must rather look back to the five “variations” contained in § 3. Chia Lin (who reads 五變 here to balance the 五利) tells us that these imply five obvious and generally advantageous lines of action, namely: “if a certain road is short, it must be followed; if an army is isolated, it must be attacked; if a town is in a parlous condition, it must be besieged; if a position can be stormed, it must be attempted; and if consistent with military operations, the ruler’s commands must be obeyed.” But there are circumstances which sometimes forbid a general to use these advantages. For instance, “a certain road may be the shortest way for him, but if he knows that it abounds in natural obstacles, or that the enemy has laid an ambush on it, he will not follow that road. A hostile force may be open to attack, but if he knows that it is hard-pressed and likely to fight with desperation, he will refrain from striking,” and so on. Here the 變 comes in to modify the 利, and hence we see the uselessness of knowing the one without the other — of having an eye for weaknesses in the enemy’s armour without being clever enough to recast one’s plans on the spur of the moment. Capt. Calthrop offers this slovenly translation: “In the management of armies, if the art of the Nine Changes be understood [sic], a knowledge of the Five Advantages is of no avail.”
7. Hence in the wise leader's plans, considerations of advantage and of disadvantage will be blended together.
“Whether in an advantageous position or a disadvantageous one,” says Ts‘ao Kung, “the opposite state should be always present to your mind.”
8. If our expectation of advantage be tempered in this way, we may succeed in accomplishing the essential part of our schemes.
信, according to Tu Mu, is equivalent to 申, and 務可信也 is paraphrased by Chang Yü as 可以伸己之事. Tu Mu goes on to say: “If we wish to wrest an advantage from the enemy, we must not fix our minds on that alone, but allow for the possibility of the enemy also doing some harm to us, and let this enter as a factor into our calculations.”
9. If, on the other hand, in the midst of difficulties we