 Dai Zhen is widely considered to be the first Chinese philosopher to have described the relation between the subject and object of comprehension by defining the subject’s potential for comprehension as a tool, which can be compared to light that makes objects visible. Xia Zhentao (1996b: 405) especially indicates his elaboration of the notions of the potential for comprehension (xin zhi shenming 心之神明), elucidation, exposure and illumination (zhao 照). Xia stresses that Dai’s reflective method, by which reality is perceived through its reflection (fanying 反映) in the human mind, pertains to basic theories of materialistic epistemology, given that the objective reality (which is external to the subject of comprehension) is seen as a necessary precondition of reflection (Xia 1996b: 405).