In comparison, the first is a concept of time-literature is a record of all kinds of knowledge. Time is like a chain, with "the present" as the clue. The former is called "the past" at this time, and the latter is called "the future" by this sound: time is history, and files produced in the past time are called historical files; Today's literature is called contemporary literature. And "now", this time chain, is extremely unstable and fleeting. When philologists began to sort out and study some contemporary documents, it actually became a historical existence. Therefore, this book uses the time concept of "historical documents". "Dependent documents are all historical documents" is to extend as far as possible when collecting documents, from ancient times to 50 years after the founding of the People's Republic of China. Secondly, from the perspective of discipline system, the broad sense of history includes the changes of nature and the initial development process of human activities. It covers a wide range of historical documents in a broad sense. It includes all the works in the world, and what we usually call historical literature refers to the history of human society, which is the so-called narrow history. Historical records refer to the historical books in the classified items of ancient times. As well as modern literature, history, philosophy, classics and other categories of literary works, any catalogue classification is relative. Therefore, all departments except the history department actually belong to historical documents, and ancient and modern academic examinations have long been discussed. Zhang Xuecheng's "Report to Sun Yuanru" said, "When inquiring about historical records, you should take multiple purposes, including classics and subsets, and you don't particularly like geography. "Zhang's argument is that the Six Classics are historical materials. As early as 2000 years ago, Sima Qian used the Six Classics as historical materials when he wrote Historical Records. He put forward the proposition of "teaching six classics in different languages and sorting out his own miscellaneous words", which was widely used. However, if the four classics are regarded as historical documents, then if we stick to the history department, we will lose to parochialism. C "If you mix and match, it's not clear. Keep it narrow "(Zhang Xuecheng: a woman's case), that is, the so-called" too much is not enough ",too wide and too narrow are drawbacks. The historical documents examined in this book are mainly branch classics in a narrow sense, while the four documents in a broad sense are summaries. Don't choose historical historical documents among them. The priorities are clear. History of China