Lu Ban's story of discovering the truth needs a summary, quick and urgent! ! !

Legend has it that once he went to the deep mountain to cut down trees and accidentally cut his hand by a leaf of wild grass. He picked the leaves and touched them gently. It turns out that there are sharp teeth on both sides of the leaf, and his hand was cut by these small teeth. He also saw a big locust on a piece of wild grass, and many small teeth were arranged on two big dies, which could quickly grind the leaves. These two things inspired Lu Ban. He thought, if there is such a toothed tool, wouldn't it be able to cut trees quickly! So, after many experiments, he finally invented a sharp saw, which greatly improved the work efficiency.