《天工开物·上篇·乃服》
第二茬的桑叶在摘取以后，第三茬叶子到秋天又长得很茂盛了，浙江人让它经霜自落，然后将落叶全都收拾起来，用来饲养绵羊，剪取更多羊毛，从而能取得更加可观的收益。
二叶摘后，秋来三叶复茂，浙人听其经霜自落，片片扫拾以饲绵羊，大获绒毡之利。
After the second batch of mulberry leaves are picked, the third batch will grow lush again in autumn. Zhejiang people let them fall off after frost and then collect all the fallen leaves to feed sheep, shear more wool, and thus obtain more considerable benefits.