Kuang Heng in Han Dynasty was very studious as a teenager. As his family is poor, he has to do a lot of work during the day to earn money. Only at night can he sit down and read. However, he can't afford candles, so he can't read when it is dark. Kuang Heng was heartbroken at this time-wasting behavior, and his heart was very painful. His neighbor's family is very rich. At night, light candles in several rooms to make them bright. One day, Kuang Heng summoned up his courage and said to his neighbor, "I want to study at night, but I can't afford candles. Can I borrow an inch of your house? " Neighbors have always looked down on people who are poorer than their family, so they said viciously and sarcastically, "Since you are too poor to buy candles, what books are you reading?" Kuang Heng was very angry after hearing this, but he was more determined.