大乘起信論義記 3.92

3.92

In the application there are two, meaning defiled and pure perfuming. Saying 'through perfuming there are marks of defilement': this reveals that the true is without marks, but manifests marks following perfuming; it also reveals that false phenomena have no substance, hence it only says 'marks'. Furthermore, according to its marks, it intrinsically has no function of reversing the flow, hence it says 'marks' and not 'function'. This is spoken in terms of following the flow in the gate of arising and ceasing, and explains what the sūtra calls 'the tathāgatagarbha is perfumed by evil tendencies', etc. Second, 'there is pure function': this is innate enlightenment tathatā within the gate of arising and ceasing, and therefore it has the meaning of perfuming; within the gate of tathatā there is no such meaning. Because of this innate enlightenment internally perfuming non-enlightenment, it causes one to produce revulsion and seeking, reversing the flow and according with the true, hence it is called 'function'. This explains what the sūtra calls 'because of the existence of the tathāgatagarbha, one can loathe the suffering of birth-and-death and happily seek nirvāṇa.' The Nirvāṇa Sūtra says: 'Due to the power of their future Buddha-nature, icchantikas will generate good roots again.' What it calls 'the power of Buddha-nature' is precisely the power of this innate enlightenment's internal perfuming. Truly, it is because one consciousness contains these two meanings that they mutually perfume each other to universally generate defilement and purity. Here, 'Buddha' is enlightenment, and 'nature' is innate; hence Buddha-nature is named 'innate enlightenment'.