When he utilises 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.
Ts‘ao Kung calls this 任自然勢 “the use of natural or inherent
power.” Capt. Calthrop ignores the last part of the sentence
entirely. In its stead he has: “So await the opportunity, and so
act when the opportunity arrives”—another absolutely gratuitous
interpolation. The _T‘ung Tien_ omits 任.