Contained in the Guliang's Commentary on The Spring and Autumn Annals, this concept embodies the ancient Chinese tradition of history compilation and historiography, and is an important historical methodology. This concept means that the research and writing of history should be based on historical documents. One needs to take an objective and prudent attitude towards different accounts in historical documents and given by different historians. One should respect historical data and refrain from making arbitrary judgments. Judgments should not be made until verification can be made; where verification cannot be made, disagreements should be allowed. This methodology is a concrete manifestation of the Chinese concept of "factual history" and expresses a well-balanced attitude of historiography.

The principle guiding the writing of The Spring and Autumn Annals is passing down both what is credible and what is unverifiable. (Guliang's Commentary on The Spring and Autumn Annals)