法華玄論 3.88

3.88

答：為釋成常無常意，故明佛性為因、涅槃為果。如來之身所以常者，良由本有佛性，見佛性故所以為常，故〈純陀品〉云「未見佛性名為無常，見佛性故常恒無變。」故佛性之因、涅槃之果更無有異，隱名佛性、顯名涅槃，亦隱名如來藏、顯則成法身，又隱則為因、顯則為果。然佛性未曾隱顯，約眾生不了故名為隱，若得了悟自為顯也。

Answer: In order to explain and establish the meaning of constancy and impermanence, it clarifies buddha-nature as the cause and nirvāṇa as the fruit. The reason the body of the Tathāgata is eternal is genuinely due to originally having the buddha-nature; because he sees the buddha-nature, he is therefore eternal. Thus the chapter "Cunda" states: "Not seeing the buddha-nature is called impermanence; because of seeing the buddha-nature, one is eternal, constant, and changeless." Therefore the cause of buddha-nature and the fruit of nirvāṇa are without difference; when concealed, it is called buddha-nature, and when revealed, it is called nirvāṇa. Likewise, when concealed, it is called tathāgatagarbha, and when revealed, it forms the dharmakāya. Furthermore, when concealed, it is the cause, and when revealed, it is the fruit. Yet the buddha-nature has never been either concealed or revealed; in terms of sentient beings not understanding, it is called concealed, but if they attain awakening, it naturally becomes revealed.