开卷有益 (kāi juǎn yǒu yì) — There Is Profit in Opening a Book

Emperor Taizong of Song set himself a reading schedule that would daunt most scholars: three volumes a day of the 《太平御览》, a thousand-volume encyclopedia he had commissioned to gather the knowledge of every book before him into a single work. On the days affairs of state kept him from it, he caught up in his spare time. His remark — recorded by the Song scholar 王辟之 in the 《渑水燕谈录》 — was a handful of characters that outlived the reign: 开卷有益，朕不以为劳也. There is profit in opening any book; I do not count it a labor.

The phrase is built from two verb-object pairs, and its force lies in what sits between them. 开卷 (kāi juǎn) means to open a volume — 卷 is the word that counts a fascicle, and the encyclopedia Taizong was reading, the 《太平御览》, was a paper 类书, not a roll of bamboo or silk. 开卷 is the act of opening a book to read. The character 益 began as a picture of water brimming over the rim of a vessel — Shuowen defines it as 饶也, abundance. 有益 states the plain result: there is gain. Set the two pairs side by side with nothing between them, and the grammar makes a conditional promise: perform the first act, and the second follows. Open a book — any book — and something is added to you.

What began as a remark about one encyclopedia widened into a defense of reading itself. 开卷 does not specify a worthy book or a fixed course of study; it covers the casual, aimless, curiosity-led reading that a stricter culture might call a waste of time. That is the phrase's quiet radicalism, and it drew a famous caveat — later readers argued that a bad book could do harm, that not every scroll repays the opening. But the mainstream reading held, and 开卷有益 settled into the characters brushed above studies and reading-room doors across China: the encouragement to the student who reads outside the syllabus, and the answer to anyone who asks what a book without a purpose is good for.

The encyclopedia in the story owes the emperor its name. Compiled over seven years and originally titled 《太平总类》, it was renamed 《太平御览》 — 御览 meaning "read by the emperor" — precisely because Taizong read the whole thousand volumes through. The phrase 开卷有益 and one of the largest reference works in the Chinese tradition therefore come from the same reign and the same reading habit: a ruler who treated a book not as a labor but as a daily gain.

In ordinary use, 开卷有益 is the phrase a Chinese parent reaches for to defend a child caught reading novels instead of studying — the gentle argument that even "useless" reading builds something, that a mind is enlarged by what it wanders through as much as by what it is assigned. It is broader than 学 (study) and warmer than 勤 (diligence): where those name effort toward a goal, 开卷有益 blesses reading for its own sake, and trusts that the gain will show up later, in a turn of phrase, a steadier judgment, or the bearing 苏轼 saw in a friend who owned nothing but what he had read.