西汉自武帝独尊儒术以后，经学成为入仕的正途。东海承人匡衡，字稚圭，出身农家，家贫而好学，年轻时曾靠替人做工维持生计。
After Emperor Wu of the Western Han made Confucianism the state doctrine, mastery of the classical canon became the road to office. Kuang Heng, courtesy name Zhigui, came from a farming family in Cheng, Donghai. Poor but devoted to learning, he supported himself in his youth by hired labour.
《西京杂记》记下了那个著名的夜晚：“匡衡字稚圭，勤学而无烛，邻舍有烛而不逮，衡乃穿壁引其光，以书映光而读之。”所谓“不逮”，是说烛光被墙挡住，照不到他家里。
The Miscellaneous Records of the Western Capital preserves the famous night: “Kuang Heng, courtesy name Zhigui, was diligent in study but had no candle. A neighbour had one, but its light did not reach him; so Heng bored through the wall and drew the light in, holding his book up to it to read.” “Did not reach” means the wall blocked the candlelight from his house.
同书还说，同县有一户人家藏书很多，匡衡去他家做雇工却不要报酬，只求“得主人书遍读之”。主人感叹，索性把书借给他，他由此博览群书。
The same book adds that a household in his county owned a large library. Kuang Heng went to work for them without asking for wages, requesting only “to read all the master’s books”. The master marvelled, and simply lent them to him; from this he read widely.
匡衡治《诗经》尤为精深。《汉书》说，当时儒生间流传“无说《诗》，匡鼎来；匡说《诗》，解人颐”——别急着讲《诗》，匡衡来了；他一开口，听的人没有不笑的。这既夸他讲得透彻，也说明他的解说极有感染力。
Kuang Heng was especially profound in his study of the Book of Odes. According to the Book of Han, a saying circulated among the scholars of the day: “Don’t expound the Odes — Kuang the Tripod is coming; when Kuang expounds the Odes, he sets his listeners smiling.” The point was both that he explained the poems thoroughly and that his teaching had remarkable power to move an audience.
凭借经学，匡衡由博士、给事中一路升迁，汉元帝时官至御史大夫，建昭三年拜相，封乐安侯。他屡次上疏，劝元帝节俭用度、重视教化，也借灾异议论朝政得失。
On the strength of his scholarship Kuang Heng rose from Erudite and Palace Attendant through one office after another, becoming Imperial Secretary under Emperor Yuan and, in the third year of Jianzhao, Chancellor, enfeoffed as Marquis of Le’an. He memorialised repeatedly, urging the emperor to curb expenditure and value education, and used omens and natural disasters to debate the conduct of government.
然而他的结局并不光彩。汉成帝即位后，有人查出他的封地因郡图错划而多占了四百顷，司隶校尉弹劾他“专地盗土”，匡衡被免为庶人，回到故乡，不久病死。
His ending, however, was inglorious. After Emperor Cheng took the throne, an inquiry found that a mistake in the commandery map had left his estate four hundred qing too large; the Colonel of the Capital Province impeached him for “monopolising land and stealing soil”. Kuang Heng was reduced to commoner status, sent home, and died of illness soon after.
更值得注意的是，为他立传的《汉书》只写了他的经学、仕途与罪过，通篇没有凿壁、借光之事。这个故事最早见于《西京杂记》——一部旧题刘歆所撰、由东晋葛洪整理传世的笔记，多记西汉遗闻，真假参半。
More telling still, the Book of Han, which gives him a full biography, records only his scholarship, his career and his crimes — nowhere does it mention a hole in the wall or borrowed candlelight. The story first appears in the Miscellaneous Records of the Western Capital, a collection of Western Han lore attributed to Liu Xin but compiled and transmitted by Ge Hong in the Eastern Jin, mixing fact with anecdote and invention.
因此，“凿壁偷光”更适合当作一个关于勤学的寓言来读：匡衡的贫寒与苦学有史可据，凿壁的细节却未必真有其事。中国人至今仍用它称赞在困境中坚持求学的人，而“偷光”只是借光，并无窃取之意。
The anecdote is therefore best read as a parable of diligence: Kuang Heng’s poverty and hard study are historically grounded, but the hole in the wall need not have happened. Chinese speakers still use 凿壁偷光 to praise those who persevere in study under hardship — and “stealing the light” means only borrowing it, with no suggestion of theft.