This essay elucidates special features of I Eonjeok’s Jungyong gugyeong yeonui and Yeonui byeoljip, mainly in comparison with Zhu Xi’s interpretation of the Zhongyong. It also explores the significance of these two works in I Eonjeok’s entire thoughts on Confucian classics. I Eonjeok understands the Daxue in accordance with Neo-Confucianism, especially when he regards the investigation of the principle [窮理] as the precondition for correcting the mind [正心]. In addition, he interprets ‘one’ [一] as the sincerity [誠] (...) of the way of Heaven and discusses it in the context of the theory of the heavenly principle and human desire [天理人欲論]. I Eonjeok understands that reverence [敬], one of the core concepts of Neo-Confucian moral cultivation, is in line with sincerity and the sagely mind. In the Jungyong gugyeong yeonui, I Eonjeok emphasizes the Nine Rules [九經] of the Zhongyong as the key principles on which one governs the world. He believes that one can fulfil this task through sincerity, and as a way of cultivation, he recommends the investigation of things, expansion of knowledge, sincerity, and correcting the mind [格致誠正] instructed in the Daxue. According to him, sincerity is construed as the way of Heaven and the King can observe the Nine Rules by getting a firm grasp of the way of Heaven. The Jungyong gugyeong yeonui was intended to be presented to the King; therefore, it exhibits strong characteristics as the disciplines of kingship [帝王學]. The Jungyong gugyeong yeonui and Yeonui byeoljip, both of which explain the Nine Rules, provide complementary explanations to each other. I Eonjeok interprets Confucius’ saying that the King should appoint a person who has the virtue of cherishing people's lives as emphasizing that the King is able to benefit the people with pity only when he is assisted by the subject with this virtue. He stresses the significance of appointing the prime minister and other ministers from the perspective of the disciplines of kingship. In addition, he believes that fortune or misfortune from Heaven depends on whether the King has consistent virtue or not. I Eonjeok is under the influence of Zhu Xi’s Neo-Confucianism in that he contrasts the heavenly principle and human desire when discussing the virtue of the King. Besides, his interpretation of the Nine Rules is deemed as the disciplines of kingship in that he underlines the pure mind of the King. (shrink)