Before Ssu-ma Kuang completed the Comprehensive Mirror, the mainstream of Chinese history had only the seventeen histories. But in the 900 years from the Sung dynasty to the present, a great many historical materials have come out. Among these, if Ssu-ma Kuang has made no reference to them and Po Yang feels they would be helpful to supplementing the contents, then he adds them in.
在司馬光完成《資治通鑑》之前，中國正史只有十七史，但是從宋朝到今天九百多年，陸續有不少史料出現，在這其間，只要司馬光沒有提及，而柏楊認為有助於充實內容者，他都補充進去。