《淮南子·泰族训》
这就好像蚕茧有抽丝的特性，但不经过女工的煮熬、牵丝，就不能成为丝线；这也好像禽卵孵化成雏，如不经过雌禽长时间的孵抱温暖，就不能变成雏。
茧之性为丝，然非得工女煮以热汤而抽其统纪，则不能成丝。卵之化为雏，非慈雌呕暖覆伏，累日积久则不能为雏。
It is like the characteristic of silkworms to spin silk, but without the women workers' boiling, cooking, and drawing out, it cannot become silk thread; it is also like the characteristic of birds' eggs to hatch into chicks, but if they do not undergo the long period of incubation and warmth from the female bird, they cannot become chicks.