This paper provides a detailed and serious investigation about the meaning of “dialectic" in ancient Greece from an etymological point of view on basis of many historical documents, disclosing a lot of new dimensions of meaning of dialectic in ancient time. Since the middle of 19th century, people have become accustomed to Hegelian and Marxian conception of dialectic and thus forgotten its original meaning in ancient Greece. It is not helpful for us to understand the essence of Greek learning and its importance in total academic history.
With his unique argument in existence and non?existence,Guo Xiang defined the vacuum as non?existence,and the invisible things as invisible existence.From these definitions was derived a series of propositions which supported his theory on emergence and transformation by itself.Regarding the human nature as the ultimate cause of the emergence and transformation, he rejected the decisive factor of the extemal cause from the very ground.He called the human nature “real nature”,“personality”,“invisible existence”,“cause of every sign”,and “heavenly principle”in different contexts. Thus he indicated the various relationships between noumenon and phenomenon and built up the individual ontological system, namely,“Ontology of human nature".In the thinking mode focused on noumenou and phenomenon,this Ontology blended with nature and ethics,solving the problem of the day.Looking at it with an eye in the course of the development,we may believe that the Ontology is also the feature of the Neo?Taoist Ontology in Wei and Jin dynasty.
