大乘起信論義記 2.106

2.106

問：若始覺異本則不成始，若始同本則無始覺之異，如何說言對始名本？答：今在生滅門中，約隨染義，形本覺說於始覺，而實始覺至心源時，染緣既盡，始本不殊，平等絕言，即真如門攝也。是故本覺之名在生滅門中，非真如門也。

Question: If incipient enlightenment is different from the innate, it would not constitute the incipient; if the incipient is identical to the innate, there is no difference of incipient enlightenment; how can one say that it is named the innate in contrast to the incipient? Answer: Now, in the gate of arising and ceasing, with respect to the meaning of according with defilement, incipient enlightenment is spoken of by contrasting it with innate enlightenment; but in fact, when incipient enlightenment reaches the source of the mind, the conditions of defilement having been exhausted, incipient and innate do not differ, being equal and beyond words, which is subsumed under the gate of tathatā. Therefore, the name of innate enlightenment is in the gate of arising and ceasing, not in the gate of tathatā.