The source is the ancient book Shangshu Yaodian.
Shangshu is the most important entry in the Five Classics, which is divided into Yu Shu, Xia Shu, Shangshu and Zhou Shu, and records ancient events.
Yaodian is the first book in Shangshu, which tells the story that Yao gave way to Shun. Yao's name is Taoren, and he is a famous leader in ancient times. Later generations respectfully call him Emperor Yao.
During Yao's reign, he was respectful and thrifty, good at observing, good at managing the world, morally prepared, gentle and tolerant, and kept the whole country in a harmonious environment. He ordered Shi and He Shi to calculate the laws of motion of the sun, moon and stars, draw up a calendar, divide a year into 366 days, and ordered cannons to control floods. However, gun spent nine years and still had no results.
The flood has not been effectively controlled, which makes Yao deeply tired. As time went on, Lao Yao was worried that he could not deal with political affairs energetically, so he looked around for successors and managed the country in good order.
At this time, officials recommended a man named Zhong Hua. Zhong Hua's father Gu Sou doesn't care about him, and his mother makes things difficult for him in every way. His brother doesn't even care about him. Despite this, Zhong Hua is still filial to his parents and cares about his younger brother. After listening to the introduction of officials, Emperor Yao married his daughters E Huang and Nv Ying to Zhong Hua to test whether Zhong Hua was really as perfect as they said, so as to observe his virtue.
Three years later, Zhong Hua was not only virtuous, but also praised by Emperor Yao. No one is more suitable to be the next monarch than Zhonghua, who is both loyal and filial. So, Emperor Yao gave the throne to Zhong Hua.
After Zhong Hua ascended the throne, he ruled the country by virtue and became a wise king. He was called Shun Di by later generations, which is what we often call Yu Shun.
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