Interpretation: you can draw tiger skin, but it is difficult to draw bones directly through skin and flesh; Metaphorically, you can know a person and what he looks like, but it is difficult to know what he is thinking. It can be explained that it is difficult to understand the essence through phenomena or unpredictable.

From: Yuan Meng Han Qing's "Kong Zhang Mu Zhi Kanmo Heluo" first fold: "Do you know who I am? It's easy to say: it's difficult to draw tiger skin, but it's difficult to draw bones. You know people's faces, but not your heart. "

Introduction of Zhang Kongmu Zhikan Mohelu: Mohelu's full name is Zhang Kongmu Zhikan Mohelu, and Mohelu is Sanskrit. It turned out to be a cry of selling children's toys. In the Yuan Dynasty, clay figurines played by children were also called "Mahalo". Plot: The play tells the story of Liu, a native of Luoyang, who sells wool for a living at home during his business trip abroad. Li Dechang's cousin, Li Wendao, was malicious to Liu Yu's mother and was severely reprimanded by Yu Niang, so she was dissatisfied. When an old man selling magic items sent a message saying that Li Dechang had made money in business, but he fell ill at the General Temple on the way and asked Yu Niang to pick him up, it happened that Yu Niang was not at home, so the old man asked Li Wendao to tell him. Li Wendao's heart was full of poison, and he pointed out that Yu Niang went to other places. He rushed to the General Temple to poison Li Dechang and took the silver. When Yu Niang finally arrived at the General Temple, Li Dechang was already dying, so he took it home and died. At this time, Li Wendao forced Yu Niang to marry him. If she does not obey, she will accuse her of killing her husband. Yu Niang would rather die than follow. As a result, the wicked Li Wendao complained first, bribed local officials and officers, and beat Yu Niang to confess. This case was discovered by a man named Justin Cheung. Regardless of his own interests, he followed a magic Luo as a clue and finally found the real murderer and protected the innocent.