The Son of Heaven refers to the emperor or monarch, the supreme ruler of an empire or dynasty. People in ancient times believed that a monarch ruled the world by Heaven’s decree and with its mandate, hence he was called the Son of Heaven. This term asserted that a ruler’s authority was legitimate and sacred, as it was bestowed by Heaven, but to some extent, it also restricted the exercise of this power. This has some similarity to the Western concept of the divine right of kings by the grace of God, but there are fundamental differences. Tian (天), the Chinese word for Heaven, is not the same as the Western term “God.” Rather, the Chinese term also implies the idea of interaction between Heaven and man, which means that the decree of Heaven also embodies popular will and popular support.