Abstract

Le Quy Don was a great talent in the history of Vietnamese ideology in feudal times. Many philosophical initiatives embodied in his works that he left behind has received much admiration. The main streams of ontological and epistemological thoughts is the thought of “Thai Cuc being one” - to be and not to be are two properties, two states of Thai Cuc. "Thai cuc being the first mixed gas", which is Le Quy Don's specific and original concept of "unique cosmology", is a core concept in his theory of Li Khi. To Le Quy Don, cognition of subjects is to cognize reasons, it means to make cognizance over its rules and natures, in order to find out internally hidden existence within the subjects. He appreciated the combination of “reasons” and “positions”, and human roles in social activities, etc.. Although Le Quy Don philosophical thought has not really broken out of dualism, idealism, mysticism, etc., his knowledges in philosophical field has been cultural works of significant value.