original_query: What is the significance of the characters that were hidden to escape the burning of books ordered by Qin Shihuang?
query: What is the significance of the characters hidden to escape the burning of books ordered by Qin Shihuang, according to Xu Shen?
answer: Xu Shen believed these characters, referred to as guwen, were the most ancient available and best conveyed the meaning of texts, as they were used by Confucius. However, later scholarship revealed them to be regional variants from the Warring States period, slightly earlier than the Qin seal script.