During the Spring and Autumn period, after Duke Xiang of Jin died, Prince Yong was to ascend the throne. However,太子夷皋 (Crown Prince Yigao) was still an infant, so his mother sought out the powerful minister Zhao Dun to discuss the succession.

Zhao Dun, fearing that the State of Qin would intervene, eventually triggered a war between the two states. Zhao Dun's arbitrary actions also caused dissatisfaction among other officials, including Grandee Jia Ji.

Later, when the Di people invaded the State of Lu, Zhao Dun dispatched Jia Ji to question Feng Shu regarding the invasion.

Feng Shu then made a insightful comparison, stating that Zhao Cui (Zhao Dun's father) was like the winter sun, while Zhao Dun himself was like the summer sun. This analogy highlighted Zhao Cui's gentle and benevolent nature, contrasting it with Zhao Dun's stern and imposing character.