From the "Li Xue Pian" by Zhao Heng (Zhenzong of Song Dynasty) of the Song Dynasty: A rich family does not need to buy fertile land, there are thousands of bells of millet in the books; there is no need to build a high hall to live in peace, there is a house of gold in the books; there is no need to go out. There is no need to hate the chariot, there are horses in the book as numerous as clusters; there is no need to hate the wife without a matchmaker, there is a woman with a face as beautiful as jade in the book; if a man wants to realize his life ambition, he diligently reads the Six Classics in front of the window. Its purpose was to encourage scholars to study for imperial examinations and participate in political affairs, so that the Song Dynasty could recruit wise men to govern the world.