大乘起信論義記 2.97

2.97

Question: What is the difference between innate enlightenment here and the above gate of tathatā? Answer: The gate of tathatā is spoken of with respect to substance transcending marks; innate enlightenment is spoken of with respect to the merits of the nature. That is, the "meaning of the great radiant light of wisdom" and so forth is named innate enlightenment. "Innate" is the meaning of nature; "enlightenment" is the meaning of wisdom. Because these are all manifested by overturning deluded defilements, they are subsumed under the gate of arising and ceasing; because within the gate of tathatā there is no meaning of overturning defilement and so forth, it is not the same as this. Therefore, the two greatnesses of substance and mark are both named innate enlightenment and are both within the gate of arising and ceasing, so that it can be endowed with the three greatnesses.