《太平广记·卷一百六十一·感应一》
《论衡》上说： 利用阳燧这种器物取火和用方诸取水，都是因为两种器物有特殊的形状，并在特殊的条件下才能够取得成功。
《论衡》曰：阳燧取火，方诸取水，二物皆当以形势得。
The “Critical Essays” says: using concave mirrors to light fires and using a whetstone to draw water are both ways of making use of objects with particular shapes under specific conditions and producing extraordinary results.