Knowing that Emperor Hui his eldest living son was "unintelligent"

Emperor Wu of Jin Dynasty still pointed him as heir. This was because if he pointed a younger son

Emperor Wu’s own getting the throne through competition with his younger brother Sima You would lose legitimacy. And forcing Sima You to leave the capital for his fiefdom would be unjustified. In order to make up for the crown prince’s lack of intelligence

selection of a wise wife for him became a major event in the Taishi period

around which fierce struggles arose. Emperor Hui’s words

deeds and thoughts were none other than normal. He was not a retarded idiot. Yet ruling a huge empire would obviously be too much for him. The reason why Emperor Wu let him stay as the crown prince was because he had high expectations for his grandson Sima Yu

thinking the latter would be a wise emperor.