This paper, based on previous studies, systematically analyzes Huiyuan’s 慧苑 interpretation of the concept of dharmadhātu, referred to as Beishi yiliu 背師異流 （betrayal of Fazang’s 法蔵 heresies）. First of all, it was Huiyuan, not Chengguan 澄観, who formulated the order and names of the Huayan 華厳 Sect’s theory of Four Realms of Reality 四法界, as he was the first to deploy the concepts of non-obstruction among phenomena 事事無碍 and the realm of non-obstruction among phenomena 事事無碍法界 as independent doctrinal terms. The earlier assertion that Chengguan established the order and names of the Four Realms of Reality requires reexamination. Secondly, in Huiyuan’s thought on the dharmadhātu, the realm of non-obstruction between principle and phenomena 理事無碍法界 and the realm of non-obstruction among phenomena occupy the same important position, and the understanding of the dharmadhātu within the framework of the expedient teaching and the true teaching 権実二教 can be regarded as an important characteristic of his view of the dharmadhātu. Therefore, there is no doubt that Huiyuan’s view of the dharmadhātu occupies an important position in the history of Huayan thought on the doctrine of dharmadhātu.
