Derives from the story of the Han dynasty literary figures Liu Xin and Yang Xiong. Liu criticized Yang's writing as too hard to understand. "You're putting yourself to hardship for no reason," he said. "Scholars today are interested in salary and profit, and can't even understand the Yijing, let alone your Taixuan Jing. I fear in the future someone will use it to cover a soy-sauce pot." But Yang Xiong only laughed.

This expression is now rare, but well known and still occasionally used by literary people.