The tentatively titled Commentary on the Nirvāṇa Sūtra （Niepan jing shu涅槃経疏） preserved in the Beijing Library北京図書館 is attributed to the Nandao sect 南道派of the Dilun school 地論宗 chiefly on the basis of its tenet classification system 教判 and its theory of co-arising of the Pure Dharma 浄法縁起. In the Commentary on the Nirvāṇa Sūtra, the Nirvāṇa Sūtra is classified as a gradual teaching 漸教, since the Buddha-nature does not manifest instantly but emerges gradually under Buddhist practice. That is to say, Dharma-nature inherently exists本有 as essence體, and to acquire the Buddha-nature, which is equivalently essence and function體用一如, practice is essential. In this way, the Commentary on the Nirvāṇa Sūtra suggests that the Buddha-nature is initially possessed始有. When illustrating the Buddha-nature, the Commentary on the Nirvāṇa Sūtra exceeds the traditional theories of future constant 當常―present constant現常, and inherent possession本有―initial possession始有, and tries to comprehend the Buddha-nature in a dynamic way along with the practice process.
