Guifeng Zongmi (780-841) was a Buddhist scholar who deeply affected both Chan and Huayan in Tang Dynasty; he was installed as fifth patriarch of Huayan School as well as a patriarch of Heze school of Southern Chan Buddhism for his integrating Chan and Huayan teaching.
Zongmi’s True Mind Ontology has dominated follow interpretations of Chan Buddhism including Yongming Yanshou (905-976) in Five Dynasties and though Yanshou affecting Shanwai school of Tiantai Buddhism in Song Dynasty, until Ouyi Zhixu (1599- 1655). Zhixu accepted Yanshou’s integrating thoughts which integrates Tiantai, Huayan, Chan, Pure Land and Secret Buddhism as one, Zhixu who was also one of the integrating Buddhism scholar in Ming Dynasty, made a book to include basic thoughts of Tiantai buddhism: Essence of Teaching and Meditation (Jiao Guan Gang Zong). Chan Master Sheng Yen has made a commentary to it: The Key of Mind of Tiantai Buddhism: A Integrating Commentary of Essence of Teaching and Meditation, Zhixu who was also the topic of Ph.D dissertation of Chan Master Sheng Yen. We can find obviously affection of Zhixu by different kinds of works of Sheng Yen.
Along the long periods of Chinese Buddhist philosophy of Mind, there are so many complicate problems among Tiantai, Huayan, Chan, Pure Land, even Yanshou and Zhixu had ever tried to solve them, but they really finish it? Thus, this paper want to ask and answer two questions above: Why Sheng Yen accepted the Tiantai Buddhism from Zhixu in his Fagu (Dharma Drumb) Chan Buddhism? Whether Sheng Yen agree with that: there is without any contradiction between true and deluded mind in the practice of Chan, or not?