Chapter 12 of Sunzi

孙Sūn子zǐ曰yuē：凡fán火huǒ攻gōng有yǒu五wǔ：一yī曰yuē火huǒ人rén，二èr曰yuē火huǒ积jī，三sān曰yuē火huǒ辎zī，四sì曰yuē火huǒ库kù，五wǔ曰yuē火huǒ队duì。

行xíng火huǒ必bì有yǒu因yīn，因yīn必bì素sù具jù。发fā火huǒ有yǒu时shí，起qǐ火huǒ有yǒu日rì。时shí者zhě，天tiān之zhī燥zào也yě。日rì者zhě，月yuè在zài箕jī、壁bì、翼yì、轸zhěn也yě。凡fán此cǐ四sì宿xiù者zhě，风fēng起qǐ之zhī日rì也yě。

凡fán火huǒ攻gōng，必bì因yīn五wǔ火huǒ之zhī变biàn而ér应yìng之zhī：火huǒ发fā于yú内nèi，则zé早zǎo应yìng之zhī于yú外wài；火huǒ发fā而ér其qí兵bīng静jìng者zhě，待dài而ér勿wù攻gōng，极jí其qí火huǒ力lì，可kě从cóng而ér从cóng之zhī，不bù可kě从cóng则zé止zhǐ。火huǒ可kě发fā于yú外wài，无wú待dài于yú内nèi，以yǐ时shí发fā之zhī，火huǒ发fā上shàng风fēng，无wú攻gōng下xià风fēng，昼zhòu风fēng久jiǔ，夜yè风fēng止zhǐ。凡fán军jūn必bì知zhī五wǔ火huǒ之zhī变biàn，以yǐ数shù守shǒu之zhī。

故gù以yǐ火huǒ佐zuǒ攻gōng者zhě明míng，以yǐ水shuǐ佐zuǒ攻gōng者zhě强qiáng。水shuǐ可kě以yǐ绝jué，不bù可kě以yǐ夺duó。

夫fú战zhàn胜shèng攻gōng取qǔ而ér不bù惰duò其qí功gōng者zhě凶xiōng，命mìng曰yuē“费fèi留liú”。故gù曰yuē：明míng主zhǔ虑lǜ之zhī，良liáng将jiàng惰duò之zhī，非fēi利lì不bù动dòng，非fēi得dé不bù用yòng，非fēi危wēi不bù战zhàn。主zhǔ不bù可kě以yǐ怒nù而ér兴xīng师shī，将jiàng不bù可kě以yǐ愠yùn而ér攻gōng战zhàn。合hé于yú利lì而ér动dòng，不bù合hé于yú利lì而ér止zhǐ。怒nù可kě以yǐ复fù喜xǐ，愠yùn可kě以yǐ复fù悦yuè，亡wáng国guó不bù可kě以yǐ复fù存cún，死sǐ者zhě不bù可kě以yǐ复fù生shēng。故gù明míng主zhǔ慎shèn之zhī，良liáng将jiàng警jǐng之zhī。此cǐ安ān国guó全quán军jūn之zhī道dào也yě。

Sunzi said: There are five ways to use fire: the first is to burn soldiers, the second to burn supplies, the third to burn baggage, the fourth to burn stores, the fifth to burn equipment. To use fire, you need favorable conditions, and these conditions must be prepared in advance. Igniting fire depends on the moment, and the fire depends on the day. The favorable moment is when the weather is dry. The favorable days are those when the moon is in the lunar mansions Ji, Bi, Yi, and Zhen. These four mansions are windy days.

In general, when attacking with fire, you must take advantage of the changes in the five types of fire and respond to them: if fire is set inside, you must respond quickly from the outside; if fire is set and enemy troops remain calm, wait and do not attack, wait until the fire reaches its peak, then act accordingly; if fire cannot be used, stop. Fire can be set outside without waiting for the inside, you must ignite it at the right time. If fire is set upstream of the wind, do not attack downstream of the wind. If the wind blows for a long time during the day, it will stop at night. Every army must know the variations of the five fires and prepare for them carefully.

Thus, using fire to aid an attack shows clarity, using water to aid an attack shows strength. Water can isolate, but cannot capture.

One who wins victories and captures territory but cannot moderate his success will perish: this is called 'squandering resources.' That is why it is said: an enlightened ruler considers it, a good general takes it into account. He does not move if there is no advantage, does not use his troops if he has nothing to gain, does not fight if he is not in danger. A ruler should not raise an army out of anger, a general should not attack out of resentment. He acts only if there is an advantage, otherwise he stops. Anger can turn to joy, resentment to contentment, but a destroyed country cannot be restored, and the dead cannot be brought back to life. That is why an enlightened ruler is cautious, and a good general is vigilant. This is the way to preserve the country and the army.