肇論疏 3.55

3.55

窮涅槃之根源，故云如此也。有名曰非眾生無以御三乘下，謂人能御法、因能成果也。然必有眾生下，既云人能御法，則先有人。既云因能成果，則後有果也。是則涅槃有始下，學而始成，故有始也。而經云涅槃無始無終湛若虛空者，無始終則不生滅，如虛空則常住也。若如虛空下，虛空不可學成，涅槃何得然耶？

[This chapter] fathoms the root and source of nirvāṇa; hence it is called thus. Where the Named says, 'Were it not for sentient beings, there would be no means to drive the three vehicles,' and so forth: It means that a person can drive the Dharma, and causes can achieve the fruit. Where it says, 'Yet there must be sentient beings,' and so forth: Since it says that a person can drive the Dharma, then first there must be a person. Since it says that causes can achieve the fruit, then afterward there is the fruit. Where it says, 'In that case, nirvāṇa has a beginning,' and so forth: Because it is accomplished only through learning, it has a beginning. As for the scripture saying that nirvāṇa has neither beginning nor end and is serene like empty space: having neither beginning nor end, it does not arise or cease; being like empty space, it is permanently abiding. Where it says, 'If it is like empty space,' and so forth: Empty space cannot be accomplished through learning; how could nirvāṇa be so?