Lü Meng (lǚ méng 吕蒙) was a meritorious general of the State of Wu during the Three Kingdoms Period (sān guó 三国时代,220-280AD). He came from a poor family and had not the chance to go to school when he was young. When he became a general, the duke of Wu encouraged him to read some books. Lü Meng took his advice, and stared to study hard. Even when he was marching or fighting, he would find time to study. There was always a book in his hand. Finally, Lü Meng became a learned general.
This idiom is used to describe being diligent in study.

中国古时候三国时期有一位将军，叫吕蒙。他小时候家里很穷，没有钱上学。当上将军以后国王鼓励他多读书。吕蒙听从了国王的建议，每天坚持学习，一天也没有间断过，哪怕是在行军打仗的时候，也挤出时间来学习，手里总是不丢开书本。后来，吕蒙终于成了一名学识渊博的将军。

手不释卷 (shǒu bù shì juàn)
【翻 译】Always with a book in hand.
【释 义】释：放下；卷：指书籍。书本不离手。形容勤奋好学。
【例 句】他是个书呆子，整天手不释卷。
【近义词】学而不厌、爱不释手
【反义词】不学无术