《梦溪笔谈·乐律一》
李阳冰所说的木质硬如石头，这样的材料也可以制琴，是让人有点闹不明白的。
木坚如石，可以制琴，亦所未谕也。
The hardness of the wood, as Li Yangbing said, is similar to stone. Such materials can be used to make qins. This part is a bit perplexing.