In contrast to Chu Hsi's theory of ke-wu (the investigation of things), Wang Yang-ming claims that there is no wu (thing/act) outside hsin (mind/ heart). Although the contrast is obvious, a reasonable and acceptable interpretation of Wang Yang-ming's thesis in this regard has yet to appear. Some previous interpretations based on Berkeley's subjective idealism, Spinoza's pantheism, Husserl's theory of intentionality, Mou Tsung-san's theory of ti and yung (substance and functioning), Putnam's internal realism, respectively, are discussed in this article. After a serious consideration of the strength and the weakness of these interpretations, I elaborate a new interpretation called "the theory of ling-qiao" (Intelligent hollow) which is more comprehensive and cogent. Under this interpretation, we can also explain the fact that the main idea of Wang Yang-ming's thesis is borrowed from religious Taoism.