I don't know how to study hard early, but I regret studying late. This sentence comes from the great calligrapher Yan Zhenqing.

"I don't know if I learn early with black hair, but I regret learning late with a white head" is a good sentence in Yan Zhenqing, a great calligrapher and poet in the Tang Dynasty.

The whole poem is: "It's a night for men to study. I don't know how to study hard early, but I regret studying hard late. " "Black hair doesn't know how to study hard early, but a bald head regrets studying at night" means: If you don't know how to study hard when you are young, I'm afraid you won't know how to study hard until you are old, and it's too late to regret it.