Career
His family belonged to the Hansan Yi clan. Yi Saek played a crucial role in the introduction and localisation of philosophy of Zhu Xi. Yi Saek resigned from all political positions after the founding of the Joseon Dynasty.
Not much is known about how he died, but some say that he was murdered while crossing a bridge, like Jeong Mong-ju (four years earlier in 1392).
When he was offered the position of Prime Minister by Yi Seong-gye, Yi Saek turned the offer down and told him that he could not serve two kings (of Goryeo and Joseon). Yi Seong-gye subsequently ordered his men to kill him if he was not able to cross the bridge in time, and if he does cross it in time, to let him go.
Yi Saek left various poetry, essays and letters compiled in The Collected Works of Mogeun.
