《天工开物·上篇·乃服》
善于分辨成熟期的养蚕人，每捉一条都会选出成熟程度恰好的蚕，这是最绝妙的地方。
捉者眼法高，一只不差方妙。
The silkworm farmers who are good at distinguishing the mature period will select the silkworms with the right maturity every time they catch one, which is the most wonderful part.