第五篇：勢(兵勢)
Chapter 5：Energy

21. 故善戰者，求之于勢，不責于人，故能擇人而任勢。

所以善於戰鬥的部隊，期望能在磅礴的氣勢和動量下取勝，不會苛求於個別的官兵， 因而能挑選正確的人依氣勢和局勢之變化完成任務。

Well-trained troops look to powerful momentum for victory, rather than ask too much from soldiers. They are able to choose right men to complete missions with given momentum under varying conditions.

22. 任勢者，其戰人也，如轉木石。木石之性，安則靜，危則動，方則止，圓則行。

依氣勢和局勢執行任務的軍隊，就好像是轉動的木頭或石頭。木頭和石頭的特性是，放在平坦的地面靜止不動，放在斜坡上則會向下滾動，如果形狀是方形靜止是常態，如果是圓形則能輕易滾動。

The troop‘s execution of a mission with developed momentum is like rolling logs or stones. The nature of a log or stone is that it remains static on a flat surface and moves down on a slope. Standstill is the norm if its shape is rectangular, but can easily roll if round.

23. 故善戰人之勢，如轉圓石于千仞之山者，勢也。

所以善於戰鬥的軍隊之氣勢，如圓形的石頭從千仞高的山上向下滾動，由此強大的位能產生的攻擊力就是動量--勢。

Thus the momentum of a well-trained troop is like that of round stones rolling down from a thousand-meter high mountain. The attacking power produced by the potential energy is the momentum.

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JSLieh