The last sentence of selling oil is "What's the difference between this and Zhuang Sheng's so-called solution?" This sentence contains two idioms. The first one is "an expert who knows cows". In fact, this idiom reveals a way of keeping in good health. Zhuangzi uses a knife to describe people, uses the body tissue of cattle to describe a complex society, and uses a knife to solve cattle to describe life. Zhuangzi believes that people can avoid being hurt if they want to find their own way of life and avoid contradictions in life. The meaning of this story is that after repeated practice, I have mastered the objective laws of things, and I can do things with ease and use them freely.
The second allusion is "Wheel Flat Wheel", which comes from Zhuangzi Heaven: I also regard it as a matter of ministers. Wheel, Xu Ken but not solid, sick but not hard, the son of the minister can't stand it, so he is old and tired at the age of seventy. Zhuangzi was a philosopher, thinker and writer in the mid-Warring States period. He has a rich imagination and can make some subtle and unspeakable philosophies fascinating. Zhuangzi's philosophical thought is "Heaven", which means that the laws of nature are irresistible and unchangeable. What we have to do is to conform to heaven and master the law. This is pure idealism, which is inconsistent with modern concepts.