是故知幽明之故。
Thus, when the sage-kings of old first appeared in the realm, they invariably made changes in the seasons, established new calendrical systems, studied the patterns of heaven, investigated changes wrought by the passage of time, and mounted spirit terraces to gaze at vital essences in the air.
」夫天文地理人情之效存於心,則聖智之府。
Thus, Yao said, “Oh you Shun!
是故古者聖王既臨天下,必變四時,定律歷,考天文,揆時變,登靈台以望氣氛。
故堯曰:「咨爾舜,天之歷數在爾躬,允執其中,四海困窮。」
The appointment of Heaven has settled now on you; adhere well to the middle way; though the people of the realm are poor and wretched, [your divine appointment will then last to the end].”6 1 Yan Yuan: Yan Hui; see 10.9, n. 32.