Cheng Guan(澄观)thought that the Awakening of Faith Sutra and the Avataṃsakasūtra were texts of the Dharma-nature school, and so extensively quoted from the former to explain the later, which obviously showed his intention of constructing Perfect Teachings(圆教)with integration of the Awakening of Faith Sutra. But according to Cheng Guan's religious classification system, the Awakening of Faith Sutra is part of Mahayana's Ultimate or Perfect Teaching (大乘终教), which is on a lower level than the Avataṃsakasūtra as Complete Teachings. The reason for Cheng Guan's classification was that he thought the teachings of Awakening of Faith Sutra pertain to worldlings and not the Buddha, although the teachings of Sutra is perfect, it is not unified with religious practice. Influenced by the Buddha-nature thought of Mahāparinirvāṇasūtra, Cheng Guan paid much attention to the difference between Dharma-nature and Buddha-nature, which resulted in his different assessment of the Awakening of Faith Sutra from that of Fa Zang(法藏).