法苑珠林 4.79

4.79

春秋感精符曰。人主與日月同明。四時合信。故父天母地兄日姊月（父天於圓丘之禮也。母地方澤之祭也。兄日於東郊姊月於西郊也）春秋說題辭曰。天之為言填也。居高理下為人經群陽精也。含為太一。分為殊名。故立字一大為天。

The Chunqiu ganjing fu says: 'The ruler of men shares his illumination with the sun and moon, and accords in trustworthiness with the four seasons. Therefore he takes heaven as father, earth as mother, the sun as elder brother, and the moon as elder sister.' (Taking heaven as father refers to the ritual of the Round Mound; taking earth as mother refers to the sacrifice at the Square Pool; taking the sun as elder brother is at the eastern suburb, and taking the moon as elder sister is at the western suburb.) The Chunqiu shuoti ci says: 'The word "heaven" (tian) means to fill (tian). Dwelling high above and regulating what is below, it serves as the constant norm for human beings and is the essence of accumulated yang. When contained, it is the Grand One; when divided, it takes distinct names. Therefore, the character is established by placing "one" (yi) over "great" (da) to form "heaven" (tian).'