Born into a family of craftsmen, Lu Ban grew up participating in many civil engineering and construction labors with his family. He always paid attention to observation and practice and sympathized with the working people. Many of his inventions facilitated their work. It is said that once when he went deep into the mountains to cut trees, he slipped and his hand was cut by the leaf of a wild grass. He picked the leaf and gently touched it, finding that the leaf had serrated edges. Lu Ban was inspired: if there was a tool with such serrated edges, it could quickly saw through trees! After many experiments, he finally invented the sharp saw, greatly improving work efficiency.

　　石磨巧思：为劳动人民减轻辛劳

　　The Ingenious Stone Mill: Alleviating the Toil of Laborers

　　据古籍《世本》记载，石磨也是鲁班发明的。一次，鲁班看到一个老太太在一点一点地用木棍磨谷物。鲁班用两块比较坚硬的圆石，各凿出密布的浅槽，合在一起，用人力或畜力使它转动，就把谷物磨成粉了。据说，刨子、曲尺、钻、凿子、墨斗等都是他发明的。这些实用工具把人们从原始、繁重的体力劳动中解放出来。

　　According to the ancient book “The Origin of the World“, the stone mill was also invented by Lu Ban. Once, Lu Ban saw an old lady grinding grains with a wooden stick bit by bit. Lu Ban used two relatively hard round stones, each with a dense array of shallow grooves, combined them, and used human or animal power to make it rotate, thus grinding the grains into flour. It is said that the plane, curved ruler, drill, chisel, and ink line were all invented by him. These practical tools liberated people from primitive and heavy physical labor.

　　云梯与钩：对军工发明的价值进行反思

　　Ladders and Hooks: Reflecting on the Value of Military Inventions