Mou Tsung-san takes the perfect embodiment of subjective being of Mind(Xinti 心體)and objective being of "Human Nature and Mandate of Heaven"(Tian DaoXing-Ming 天道性命)as the model of Confucian round teaching. In this paper, it is further defined as sudden enlightenment(Dunwu 頓悟)of ren(仁). Cheng Mingdao is taken as one holding the round teaching by the approach of returning to the Being of Mind(Xinti 心體) from the objective being of "Human Nature and Mandate of Heaven"; whereas Luo Jinxi is considered as the one who expands the Being of Mind (Xinti 心體)the objective being of "Human Nature and Mandate of Heaven"; hence, they both have ren as their core concept. The sudden enlightenment of ren can be further developed into the idea of paradoxical sudden enlightenment(guijue dunwu 詭譎頓悟)of opposites, which is the ultimate Confucian round teaching. Hu Wufeng's asserting that heavenly principles and human desires exist in the samebody but taken for different uses, is as much as what Luo Jinxi said that "lifting your head and raising your eyes, opening your month and speaking your words, are all expression and manidestation the Being of liang-chi ( 知體) ", both imply the paradoxical sudden enlightenment of opposites. In this way, we could make clear the true connotations of the practical of Dao(Juewu 覺悟)put forward by Luo Jinxi and also complete the Confucian critique and classification of all doctrines within a system.