唐代大诗人杜甫的好友郑虔,既善作诗,又能绘画,还写得一手好字.一次,郑虔的一幅题诗画被献到皇帝唐玄宗那里,玄宗看了拍案叫绝,当下御笔写了“郑虔三绝”四个字.郑虔的字写得好,诀窍当然在于“练”,但是他的练字,却与铁杆庄稼——柿树的叶有点关系.据《尚书故事》载:“郑广文(郑虔)学书而病无纸,知慈恩寺有柿叶数间屋,遂借僧房居止.日取红叶学书,岁久殆遍.”古有“柿叶可以临书”的说法,就是由这个故事而来的. Zheng Qian, a friend of Du Fu, a great poet of the Tang Dynasty, was both a good poem and a good poet, and a good poem was written in Zheng Qian’s poem, which was presented to the emperor, Emperor Xuanzong. Zheng pen wrote the “Zheng Qian three must.” Zheng Qian’s word well, the trick of course lies in “practice”, but his practice, but with iron crops - persimmon leaves a little relationship.According to “Shang Shu Story ”contains:" Zheng Guangwen (Zheng Qian) learning the book and the disease is no paper, that Ci En Temple have persimmon leaves several rooms, then monks room home. It is from this story that we can come to the book.