This paper is a second-order study of xinxue 心學 (the Neo-Confucian theory of mind from the Lu-Wang school). Having shown the difficulty of fitting the theory into philosophical or religious discourse, the paper will argue that it is more appropriate to see xinxue as a special variety of the “discourse of the infinite,” that is, discourse concerning the infinite, which will bring forth action. In this light, Lu Xiangshan 陸象山 and Wang Yangming’s 王陽明 theory on the internal experience of the unity of mind is to be seen less as description of mental life than as an effort to adhere to the spirit of Mencius: they insist on the unity of the internal experience of mind, without allowing its intensity to be reduced in the explanatory theory of lixue 理學 (theory of principles) espoused by Cheng Yi 程頤 and Zhu Xi 朱熹, and, in this way, strive to reaffirm Mencius’s proclamation about the goodness of human nature. More importantly, the discourse as a whole works to enhance the status of the sage as someone who embodies tianli 天理 (the highest moral principle of the universe). This mode of discourse has the performative force of bringing forth moral actions. The real subject of xinxue is not what Lu and Wang claim it to be, e.g. the essentially good human nature or the infinite moral mind. Rather, the subject of xinxue is that which reveals itself through a series of effortful discursive activities and in the moral practice thereby produced. The subject of xinxue that emerges from this continuous process of striving is a special subject even within the Confucian tradition, whose attention is directed mainly towards the internal experience of the unity of mind. This subject threatens to interrupt the intellectual as well as socio-political operations established by lixue, and therefore engenders a series of conflicts.