Yan Zhenqing's is the "night light", which is when people are studying. Black hair doesn't know how to study early, and Bai Shoufang regrets studying late. "
"If you have a constant, why do you want to sleep at night? The most useless thing is that it has been cold for ten days. " This is a couplet written by Mao Zedong based on Yan Zhenqing's poems.
It means that as long as you have perseverance, why get up early and go to bed late every day. The worst thing is to take a day off for ten days.