虚实篇 NO.7：

夫兵形象水，水之形，避高而趋下，兵之形，避实而击虚。

水因地而制流，兵因敌而制胜。

故兵无常势，水无常形。

能因敌变化而取胜者，谓之神。

故五行无常胜，四时无常位，日有短长，月有死生。

这句啥意思：

兵的性态就象水一样，水流动时是避开高处流向低处，用兵取胜的关键是避开设防严密实力强大的敌人而攻击其薄弱环节；

水根据地势来决定流向，军队根据敌情来采取制胜的方略。

所以用兵作战没有一成不变的态势，正如流水没有固定的形状和去向。

能够根据敌情的变化而取胜的，就叫做用兵如神。

金、木、水、火、土这五行相生相克，没有哪一个常胜；四季相继相代，没有哪一个固定不移，白天的时间有长有短，月亮有圆也有缺。万物皆处于流变状态。

英文这么说：

Military tactics are like unto water; for water in its natural course runs away from high places and hastens downwards. So in war, the way is to avoid what is strong and to strike at what is weak.

Water shapes its course according to the nature of the ground over which it flows; the soldier works out his victory in relation to the foe whom he is facing.
Therefore, just as water retains no constant shape,so in warfare there are no constant conditions.
He who can modify his tactics in relation to his opponent and thereby succeed in winning, may be called a heaven-born captain.
The five elements (water, fire, wood, metal, earth)are not always equally predominant; the four seasons make way for each other in turn. There are short days and long;the moon has its periods of waning and waxing.

《五行简介》