Yaeun Gil Jae(1353~1419) who lived at the end of Koryeo dynasty throughout the early Joseon Dynasty, was a person praised as a synonym for loyalty. He lived this turbulent period to realize his Confucian ideals faithfully. Even though he left a small number of writings and he didn't show a clear political activities, he remained in history as the loyalist who kept the fidelity and became the subject of praise by many Joseon Dynasty's scholars. His Confucian ideas of fidelity and determination to abandon secular interests by choosing the path of retreat, and the contribution to the birth of a group of scholars called Sarim(士林;forest of scholars) by teaching his disciples through his pure academic practice were noted to later studies. Sometimes, though often he has been the subject of controversy, the position of Gil Jae as one of the few loyalists of Koryeo was unshakable.
His writings handed down now, the articles of the later people praising about him occupies much more than the articles wrote himself. The Praises for Gil Jae continues until the king Jeongjo from the early Joseon, and from the kings to the scholars of the country.
His loyal spirit was the expression of the willingness to follow the Confucian values at the political situation of the end of the Koryeo dynasty. His awareness of reality and career mind are exposed to the poetry he left. With a calm and plain style, it represent his Confucianism values that can't be shaken to social conditions. Sometimes it expressed sorrow to the collapse of the country with his former colleagues, but also describes the attitude of the An-bin-nak-do(安貧樂道; being content amid poverty and taking pleasure in acting in an honest way) by being obedience to the will of heaven and unshaken to the secular interests. The fidelity of Gil Jae was praised by Kwon Keun and others from the time he lived, but the earnest veneration starts with the compilation of 『Illustrated Guide to the Three Relationships(三綱行實圖)』at the period if king Sejong. He is recorded in the book with Jeong Mong-ju(鄭夢周) as the symbol of loyalists. Since with the advent of Sarim, Gil Jae was granted as the initiator and connector of the Joseon's neo-Confucianism, and his loyal spirit has continued to be praised. In this background there was the intention of Sarim tried to link Gil Jae with Jeong Mong-ju, but also he concentrated on cultivating a new generation of neo-Confucian scholars including Kim Suk-ja and his son Kim Jong-jik, the famous Neo-Confucian scholars. He had promote the study style of the Sarim leading up to Jo Shik(曺植) with his faithful academic attitude that practice the values of the 『Sohak(小學; The Elementary learning)』
Modern Significance of fidelity of Gil Jae in these times of selfishness and materialism, are that he chosen his own way of suffering, rather than the secular interests. The loyalty of this age is not about the monarch, neither personal or group interests, but should be for the benefit of the larger public. Depending on their Cheon-myeong(天命; fate of heaven) each person should fulfil on doing the will of the people and the interests of the public and be fidel to their ideal not to their interests.