According to Cha Zhenren. Mr Zhang Han is a master of Taoism and Yi-ology. Professor Zhang Han's Yi-ology is recognized by the state, and he has a lecturer's certificate issued by a formal national institution, so Mr. Zhang Han's lecture on Yi-ology is reliable.
Yi-ology is a philosophical knowledge that studies the operating rules of all things and their interrelationships under the guidance of the corresponding academic thought of heaven and man. Since the Spring and Autumn Period, China's scholarship has always been integrated with Yi-ology.