大乘起信論義記 2.242

2.242

引證中依於此義乃至涅槃者，依此同相門，如上本末不覺本來即真如，故說一切眾生性自涅槃不更滅度，故經云「一切眾生即涅槃相不復更滅。」言菩提之法乃至無得者，依此同相門，如上始本二覺，即是真如，故諸佛菩提非修得也。又前約不覺即如故，眾生舊來入涅槃；今約覺亦即真故，諸佛菩提無新得也。言非可修相者，望前涅槃非是了因修顯故。言非可作相者，望前菩提非是生因所作故。畢竟無得者，此之二果即性淨本有，故無得也。

In citing proof, "relying on this meaning... nirvāṇa" means: relying on this gate of the mark of sameness, since the aforementioned fundamental and derivative non-enlightenment are fundamentally identical to tathatā, it is said that the nature of all sentient beings is intrinsically nirvāṇa and does not undergo extinction again. Hence a sūtra says: "All sentient beings are already the mark of nirvāṇa and do not become extinct again." As for "the dharma of bodhi... unobtainable": relying on this gate of the mark of sameness, since the aforementioned incipient and innate enlightenments are precisely tathatā, the bodhi of the buddhas is not obtained through cultivation. Furthermore, previously, with respect to non-enlightenment being identical to tathatā, sentient beings have from of old entered nirvāṇa; now, with respect to enlightenment also being identical to tathatā, the bodhi of all buddhas is nothing newly obtained. "Not a mark to be cultivated" means that, looking back to the aforementioned nirvāṇa, it is not cultivated and revealed through revealing causes. "Not a mark to be made" means that, looking back to the aforementioned bodhi, it is not produced by generative causes. "In the end is unobtainable" means that these two fruits are fundamentally possessed as naturally pure; hence they are unobtainable.