大般涅槃經義記 8.54

8.54

「如汝所說乳無酪」下釋第六難，先牒難辭，下對顯非，於中初法，次喻，後合。法中，「愚人作如是說」呵邪乖正，「智終不言」辯正異邪。「何以」下釋，「以無性故」智不言有。喻中三句：一「無緣」下出證酪本無、二「如水乳」下異緣不出證酪本無、三「頗求」下得緣方出證酪本無。下合顯法，「佛性如是」合乳酪性假緣可見，「假緣可得」合得頗求即便成酪，「待緣後成即是無性」合若本有何故待緣。

From 'As you have said, that milk lacks curd' downward, he resolves the sixth objection. He first cites the words of the objection, and below shows in response that it is incorrect. In this, there is first the doctrine, next the metaphor, and afterward the application. In the doctrine, 'Foolish people make such statements' rebukes the heterodox for deviating from the correct; 'the wise never say' distinguishes the correct from the heterodox. 'Why is this?' and so forth explains: 'Because there is no nature [as curd in the milk],' the wise do not speak of it as existing. In the metaphor there are three clauses: First, from 'Without conditions' downward proves that curd is fundamentally absent; second, from 'Like water and milk' downward proves that under different conditions it does not come forth, proving that curd is fundamentally absent; third, from 'Seeking everywhere' downward proves that only upon obtaining conditions does it come forth, proving that curd is fundamentally absent. Below, the application reveals the Dharma: 'The buddha-nature is like this' corresponds to the nature of milk and curd being visible dependent on conditions; 'attainable dependent on conditions' corresponds to immediately becoming curd upon obtaining the conditions sought; 'being completed only after depending on conditions is precisely being without nature' corresponds to: if it existed fundamentally, why would it depend on conditions?