when he utilizes combined energy, his fighting men become as it were like unto rolling logs or stones. for it is the nature of a log or stone to remain motionless on level ground, and to move when on a slope; if four-cornered, to come to a standstill, but if round-shaped, to go rolling down.

故善战人之势，如转圆石于千仞之山者，势也。
thus the energy developed by good fighting men is as the momentum of a round stone rolled down a mountain thousands of feet in height. so much on the subject of energy.

【注：】①：“瑕”的“王”旁换“石”旁。