故善戰者，求之於勢，不責於人，故能擇人而任勢。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。故善戰人之勢，如轉圓石於千仞之山者，勢也。
The ones who thrives in battle, knows how to spot and rely on the macro momentum/opportunities rather than over-relying on the soldiers to turn the tide. Identifying the momentum and then tune the people to ride it is similar to rolling a tree log. When the ground is flat, the log is still, when the ground is steep, it moves by itself, if the log is square, it is stopped, when the log is round, it rolls. One who master this understanding would be as if rolling down a rounded log down a very steep slope.
– Understanding –
It is important to understand where the cycle is. Akin to Ray Dalio explanation of economic cycles, it is comparatively much easier to ride a huge macro wave up than to oppose one.
Momentum is important, winners win more (business wise).
It is far easier and safer to roll a snowball down a steep hill than rolling a snowball up one.