《宋书·志·卷十二》
所以《虞书》写出了对天钦敬的典式，《周易》明确了制定历法的法则，说到历法应该迁就天象而求符合，而不是用符合来作为检验天象的标准。
是以《虞书》著钦若之典，《周易》明治历之训，言当顺天以求合，非为合以验天也。
Therefore, the "Yu Book" writes out the model of reverence for heaven, the "Book of Changes" clearly defines the laws for making the calendar, and says that the calendar should be accommodating to the celestial phenomena and seek to conform to it, rather than using conformity as the standard for testing the celestial phenomena.