According to legend, there was a poor scholar in the ancient state of Chu. When he was reading Huainanzi, he learned that the leaves hidden by mantis when catching cicadas can be used for invisibility. Next morning, he went to the forest. He looked around and finally found the invisible leaf. The poor scholar was ecstatic. He picked the leaves carefully, but the poor scholar accidentally missed the leaves, fell to the ground, mixed with other leaves and couldn't find them. So the poor scholar took all the leaves home, and the poor scholar tried one by one, asking his wife while trying; Do you see it? The wife replied; "I can see that." In this way, I asked again and again, and finally my wife got bored and said, "I can't see it." The poor scholar was full of joy and went out to steal with this leaf. In this way, the poor scholar was sent to the yamen by the shopkeeper. Later, the magistrate asked the scholar why he stole something, and the poor scholar told the story again. Finally, the poor scholar said a word: "A leaf can't see Mount Tai!"