This experimental essay intends to analyze interpretational cases related to the understanding of the Mencian theory of human nature. The first part introduces straightforward reading by a representative sinologist, historian, and philosopher. The second part discusses two examples that reinterpret the Mencian theory in an injective way with the Kantian theory and processing philosophy, respectively. The third part reexamines our understanding and evaluation of human nature in the Mencian theory using new discoveries of experimental psychology. The claim that there exists (...) a foundation of goodness in human nature has been revealed by both Mencius and modern psychologists from their own perspectives. It should be meaningful to further examine the rationale of acceptance of these theories. Such study also contributes to establishing a right attitude towards people and human societies, which in turn will influence the quality of our life in the long term. (shrink)