大般涅槃經義記 7.54

7.54

「云何不生不生不可說」者牒問第四，言「不生者名為涅槃」辯前不生涅槃常寂故曰不生。「涅槃不生故不可說」釋後不生不可說也。涅槃從緣有可生故，不可定說為以不生。「何以」下釋，從修證得義說為生，非是辦無令有名生，是中不欲明涅槃生，舉彼涅槃不生之法有可生義，類顯世間不生之法有生義矣。

"How is it that the non-arising of non-arising cannot be spoken of?" cites the question regarding the fourth. The statement, "The non-arising is termed nirvāṇa," identifies the prior non-arising; because nirvāṇa is eternally tranquil, it is called non-arising. "Because nirvāṇa does not arise, it cannot be spoken of" explains that the subsequent non-arising cannot be spoken of. Because nirvāṇa has [the meaning of] being capable of arising dependent on conditions, it cannot be definitively spoken of as non-arising. Below "Why?", it explains: it is spoken of as arising in the sense that it is attained through cultivation and realization, not that bringing something out of nonexistence into existence is called arising. Here, it does not intend to state that nirvāṇa arises; rather, by adducing the fact that the non-arising dharma of nirvāṇa possesses the meaning of being capable of arising, it by analogy reveals that worldly non-arising dharmas possess the meaning of arising.