成唯識論述記 7.235

7.235

述曰：「雖亦麁動」，「亦」者，顯不定義，謂亦五識。又顯自識行兼有細，以麁亦細也；又顯與第七、八識行相異，彼微細沈審故；又所藉緣少易辨故，無時不具。若爾，何故不一切時如第七、八相續生耶？答：由違緣故，有時不起。何者是違緣？即下五位，或厭於心，或異緣礙，遮識生起，故名違緣。

The Commentary states: Regarding “although it is also coarse and fluctuating”: “also” expresses an indeterminate meaning, indicating that it is like the five consciousnesses. It also indicates that its own consciousness’s activity also includes what is subtle, for being coarse it is also subtle; it also indicates that it differs from the modes of activity of the seventh and eighth consciousnesses, for those are subtle, deep, and reflective; further, because the conditions it relies upon are few and easily assembled, there is no time when they are not complete. If so, why does it not arise continuously at all times like the seventh and eighth? Answer: Due to adverse conditions, there are times when it does not arise. What are the adverse conditions? They are the five states below: either revulsion toward the mind, or obstruction by other conditions, blocking the arising of consciousness; hence they are named adverse conditions.