유교는 현실, 그리고 현실에서의 실천을 중시하는 학문으로 핵심 기능은 經國治世라 할 수 있다. 유교는 고려조에서 風敎와 經世의 주축이 되었다. 牧隱李穡(1328~1396)은 孔子에 대해 “인류가 생겨난 이후로 공자보다 훌륭한 분은 나오지 않았다”고 극찬하면서 자신의 道統觀을 밝혔다. 이색은 堯舜의 도를 계승하겠다는 확고한 의지를 지닌 순수한 儒者였다. 한결같이 유교의 현실참여와 실천정신을 중시하였으며, 유교적 관점에서 도교와 불교를 비교하면서 저들의 설을 일부 인정하였다. 이색은 어려서부터 여러 山寺에서 독서하면서 많은 승려들과 교유하였다. 그는 승려들이 父子間에 天倫을 끊고 형제간에 人倫을 저버린 것에 대해 비판하면서도, 유교가 사회적 제 기능을 하지 못했던 현실 속에서 불교가 쇠퇴한 風敎의 역할을 담당할 것으로 생각하였다. 이색은 유교적 관점에서 道仙을 수용하였다. 유교는 자기수양을 철저히 해야 하고, 까다로운 예의와 법도를 중시하는데 반해 노자의 도는 無爲自然하는 것이다. 道仙은 사람들이 만들어 놓은 사회적 법규로 인해 야기된 폐해로부터 백성들을 구제해주는 濟世의 역할을 담당하는 것이다. 이색은 道仙의 개선점으로 노자의 말인 참 진리를 따르지 않고 괴이하고 허무맹랑한 술법으로 惑世誣民하고 세상을 어지럽히는 것을 비판하였다. 老子의 道를 빌려 쓰면서 실상은 노자의 도와 전혀 딴판으로 가르치는 것은 스승을 욕되게 하는 것 이라고 경계하였다. 이색이 유·불·선 삼교를 논할 때 가장 중시하였던 것이 진리에서 벗어났느냐 아니냐 하는 것이었다. 이색은 유·불·선에서 취할 만한 말은 취하였다. 그는 기본적으로 공자·석가·노자의 말이 크게 다르지 않다고 보았다. 그가 불교와 도교를 원융적 차원에서 포용할 수 있었던 배경이 여기에 있다.

Confucianism is the study of scholars who actively participate in the real world and place emphasis on moving into what they learn. MogEun LeeSack (李穡, 牧隱 1328~1396)consistently emphasized the participation and practice spirit of Confucianism and compared Taoism with Buddhism from a Confucian point of view. Confucianism is the role of government that governs countries and people. In other words, it became the main force that governed the world that it was able to correct the order of the Goryeo society which was confused at that time and to be able to edify it as a national religion. In other words, MogEun said about Confucius that he succeeded the Way of King Yo· Sun, revealed the law of Wen·Wu, organized and compiled the Book of Odes· the Canon of History, enacted Proprity·Music to come true Right politics. He taught people correctly and taught them to be right and to have a good temperament, so that they provided a basis for enjoying peace and happiness. He also praised the fact that people have not been better than Confucius since the beginning of the world. At the same time, he expressed his legitimacy of the Way. In addition, he was a pure Confucian with a firm will to inherit the intention of Yo·Sun and partly recognized the idea of Buddhism and Taoism in a neo-Confucian worldview. From his early age, 牧隱had learned from many mountains and temples including Sungjusan, and cultivated his academia and friendship with many monks. The monks, however, threw out their positions and official uniforms, broke the tie endowed by Heaven between the father and the son, and abandoned the human bondage in the brotherhood. He revealed his Buddhist image that the Confucian had rejected Buddhism as they became a group like a fowl. The reason why they did not reject Buddhism was that Confucianism could not play a role in correcting the social order, and that Buddhism would play a role of reforming the deterioration of the beautiful and fine custom. In other words, Buddhism has been able to save rebirth from misery and suffering, to be mentally dependent, and to be able to take on the role of salvation even further. It accepts Taoism from a Confucian point of view. Confucianism has to thoroughly discipline self-discipline, emphasize strict courtesy and law, and yet, the Way of Laozi is natural to do so. He seemed to recognize Taoism as a reliever who relieved the people from the harm caused by the social laws and regulations that people made. However, as an improvement of Taoism, it is difficult to follow the true truth of Laozi, to make some people hate and disturb the world with strange and impractical methods. And he stressed that the false Taoists who deceive the people and confuse their minds should try to understand and uncover the teachings of Lozai. In other words, he warned Taoism that he borrowed the Way of Laozi and taught the reality in a way totally different from that of Laozi, and to dishonor the Master. In MogEun’ thought, there is no Way to leave the reality. If people see only what is visible, or if they follow the ideal quibbling over too much reason, they will fall into a heresy. In criticizing Confucianism, Buddhism, and Taoism, MogEun regareded it as the most important thing whether they are escaped from the Truth(the Way). Among the ideas of the Confucianism, Buddhism, and Taoism, MogEun took something that he could take, and criticized the words that fell into the heresy or were absent-minded. The words of Confucius, Buddha and Laozi are not much different. Therefore, he could embrace Buddhism and Taoism in a futuristic way without being greatly rejected.