Inventing is a combination of brains and materials. The more brains you use, the less material you need.

Inventing is a combination of brains and materials. The more brains you use, the less material you need.

发明是大脑和材料的结合。你用的脑子越多，你需要的物质就越少。

-- Charles F. Kettering 查尔斯·凯特林