成唯識論述記 4.33

4.33

The Commentary states: The inference is: the eighth should take the seventh as its co-nascent support; because it is of the nature of consciousness; like the sixth consciousness. This has the fallacy of inconclusiveness with the five consciousnesses, so it should say: because it is admitted to be of the nature of consciousness and not the five consciousnesses. This too is not so, for the seventh consciousness is admitted to not be the five consciousnesses, because it is of the nature of consciousness. One should generally say: the eighth in principle ought to have a co-nascent support; because it is of the nature of consciousness; like the eye and other consciousnesses; because this property does not say it takes the seventh as support, there is no fallacy of inconclusiveness. Thus, although it says it serves as support for the evolving consciousnesses, through this reason it shows that the eighth takes the seventh as support. Or if it were not so, what was previously said—that manas takes the eighth consciousness as its co-nascent support—would have the fallacy of inconclusiveness, because the eighth would have no co-nascent support; therefore it says the eighth also has a co-nascent support. Here there is no dispute over the immediately preceding condition or the causal seed; the causal seed is the previous line, hence both dispute the co-nascent.