《论衡·卷十·非韩篇》
所以一件事或许看来没有好处而好事却要靠它，一件事或许看来没有直接效果而有直接具体效果的事却要依靠它。
故事或无益，而益者须之；无效，而效者待之。
Therefore, something may seem to be of no benefit, but good things depend on it; something may seem to have no direct effect, but things with direct and specific effects depend on it.