《晋书·志·第八章》
少昊时，依据燕子归来之类的物候判断分至；颛顼、帝学时，重黎掌管天；唐帝、虞舜时，羲和掌管日，三代时沿袭了这种传统，每个朝代都有日官。
乃自少昊，则玄鸟司分，颛顼、帝喾，则重黎司天；唐帝、虞舜，则羲和掌日，三代因之，则世有日官。
During the time of Shaohao, the time of solstice was determined by observing natural phenomena such as the return of the swallows. During the time of Zhuanxu and Emperor Xue, Zhongli managed the heavens. During the time of King Tang and Emperor Shun, Xi and He managed the sun. This tradition was passed down to the Three Dynasties, and each Dynasty had a sun official.