許慎
In the postface, Xu gives a brief account of the history of writing. According to legend, Chinese characters were first invented by Cang Jie, who was inspired by footprints to create a system of signs that refer to the natural world. These original graphs could then be combined to make meaningful characters with referents distinct from their component graphs. This was important for Xu Shen, who emphasized the productivity, even fertility, of Chinese writing. Despite the novel meanings of compound characters, Xu Shen believed that true understanding of composite characters was contingent on an understanding of their components. Providing clear explanation of these relationships lay at the heart of his motivation.