In the Shiji, Sima Qian introduces Boyi and Shuqi’s story as an old tradition: they were sons of the ruler of Guzhu, an ancient state. Their father wanted Shuqi to inherit. When he died, Shuqi yielded the position to his older brother. Boyi answered that their father’s decision should stand and left. Shuqi also refused the throne and went away. Their people then chose another son.
The brothers’ first act is a refusal: each treats the other’s claim as stronger than his own. Their quiet departure sets the terms for the harder choice that follows.