TAN Si-tong was the first modern Chinese philosopher who provided a systemic explanation of human brain, based on which he also studied the identity between people and the world. By investigating the cognitive process, he confirmed that cognition is started by contacting things with sense organs such as eyes, ears, the nose, the tongue and the body. This is to some extent an empirical theory of reflection. While exaggerating the contradiction between the limit of human sense organs and the infinite of the exterior world, and highlighting the constant change of cognitive objects, TAN denied the possibility of knowing the world with sense organs and sought a new cognitive approach, that is, seizing the truth via Buddhist doctrines of the "consistency of one and many" and the "simutaneous existence of the future, the present and the past". In this way, "transforming knowledge of karma into wisdom" becomes the ultimate aim of his cognitive philosophy. TAN's cognitive philosophy is unique in its combination of Buddhist meditation and enlightenment on the one hand and an empirical theory of reflection from a positivist approach of natural sciences on the other.