My understanding of cattle means that I was not familiar with the physiological structure of cattle at first. When I get to know cows, I only see the external shape of cows, and I often chop bones with a knife, so I have to change the knife every three months. After three years, I know the physiological structure of cattle like the back of my hand, but I often use a knife to cut muscles when I understand cattle, and I have to change the knife once a year. Later, I thoroughly mastered the method of understanding cattle, and I could follow the natural texture without looking. The wall is empty, and the knife is still new in nineteen years. . This is about Zhuangzi, not Liang. It's from Zhuangzi. Health. " At first, he violated the physiological structure and injured his knife when trying to solve the cow, which was against health. Compare a knife to an adult.