大乘起信論別記 1.158

1.158

「細中之細」，後中後一。以前中初二俱在意識，行相是麁，凡夫所知；前中後一是第七識，行相不麁，非凡所了；後中初二能所差別，菩薩所知；最後一者，見相未分，唯佛窮了。此下明滅盡義。將說滅義，先明智緣。

"Subtle among the subtle" refers to the last one of the latter. Because the first two of the former both reside in the manovijñāna, their mode of activity is coarse, known to ordinary beings; the last one of the former is the seventh consciousness, its mode of activity not being coarse, not understood by ordinary beings; the first two of the latter have the distinction of subject and object, known to bodhisattvas; and the very last one has not yet divided into perceiver and perceived, understood thoroughly only by the Buddha. Below this, the meaning of complete cessation is explained. Intending to explain the meaning of cessation, he first clarifies the cognitive conditions.