Zhu Xi ñ¹ýø draws a parallel between the philosophies of Lu Jiuyuan ëÁÎúæÐ and of Gaozi Í±í more than several times. Would Lu agree to this supposed similarity? In an epistle to Zhu Xi written in 1188, Lu describes their debate over Gaozi¡¯s unmoved mind (budongxin ÜôÔÑãý) which took place in 1181 at the Bailudong ÛÜÖãÔ× Academy in Nankang ÑõË¬. According to this epistle, the two expressed conflicting views on the earlier philosopher so strongly as to call each other ¡°Gaozi¡± in an offensive manner. This dissension largely results from their dissimilar interpretations of the concept of budongxin. Zhu Xi interprets this concept as buhuo Üôûã which means not only fearless but more importantly no doubt or query. Therefore, Zhu Xi emphasizes ¡°understanding words¡± (zhiyan ò±åë) and ¡°penetrating the principle¡± (qiongli Ïã×â), and argues that one should first understand words before nurturing one¡¯s qi (yangqi å×Ñ¨). In contrast, Lu Jiuyuan understands budongxin as a method of moral cultivation to attain Confucius¡¯s ¡°standing firmly at thirty¡± (sanshi er li ß²ä¨ì»Ø¡). In other words, it is a way of establishing oneself as a true moral agent. Unlike Zhu, Lu makes no mention of zhiyan when he discusses budongxin; he only refers to yangqi. As a result, he fails to explain where human morality originates from, and how one establishes oneself as a moral agent. According to Lu, understanding words is a prerequisite for knowing others (zhiren ò±ìÑ). Knowing others does not mean understanding one¡¯s outward actions but it means perceiving the true virtue (de Óì) of others. Its aim is to fully grasp and rightly criticize false theories and actions. Therefore, according to Lu, one can understand words after completely understanding dao Ô³, that is, after succeeding in moral cultivation. In other words, Lu believes that one can understand words only after one becomes a true moral agent by nurturing qi. The different positions between Lu and Zhu are inherited and further analyzed by Wang Fuzhi èÝÜýñý and Huang Zongxi üÜðóýý respectively, and exert profound influence on many traditional annotators as well as modern scholars such as Tang Junyi ÓÐÏÖëö, Li Minghui ×ÝÙ¥ýÇ, and David S. Nivison.