Poems describing reason

black hair doesn't know how to study early, but white head regrets studying late. -Yan Zhenqing's "Poetry to Encourage Learning"

The lights are on at five o'clock in the middle of the night, which is when men are studying. -Yan Zhenqing's "Poetry of Encouraging Learning"

The ancients learned nothing, and it took time to grow old. -Lu you's "Reading on a Winter Night and Showing Your Child"

I have a shallow understanding of the paper, and I don't know how to do it. -Lu You's Reading on a Winter Night

though a country be sundered, hills and rivers endure, and spring comes green again to trees and grasses. -Du Fu's "Spring Hope"

Reading is already deep in spring, and an inch of time is worth an inch of gold. -Wang Zhenbai's "Two Poems of Bailudong, Part One"