《淮南子·诠言训》
参加斗殴的双方都十分强壮，但却都受这一瘦弱者制约，不是因为瘦弱者骁勇，而是因为瘦弱者本身没有参与这场相打斗殴。
两人相斗，一赢在侧，助一人则胜，救一人则免，斗者虽强，必制一赢，非以勇也，以不斗也。
The two fighting people are all very tough, but they are both restrained by this thin person, not because thin people are brave, but because thin people do not themselves participate in the fight.