大方廣圓覺修多羅了義經略疏 1.783

1.783

上皆釋竟。然八識中不言第七者，義當見聞等塵也。以七合第八，名見等塵。故《瑜伽》云：「賴耶識起必二識相應。」又七合第六，名見等塵，以意識緣外境時，必內依末那為染污根方得生起故。故上引論云：「即依此相續識，乃至名為意識故。」論及此經所列無別末那，《楞伽》亦爾，皆由第七計內為我，合於轉相；計外我所，合於事識。若不連前帶後，則顯示心數相躡生起，義不便故。

The above have all been explained. However, the reason why the seventh consciousness is not mentioned among the eight consciousnesses is that its meaning corresponds to the dust of seeing, hearing, and the rest. By combining the seventh with the eighth, it is called the dust of seeing, etc. Thus the Yogācārabhūmi says: 'When the ālayavijñāna arises, it necessarily corresponds with two consciousnesses.' Furthermore, combining the seventh with the sixth, it is called the dust of seeing, etc., because when the mental consciousness conditions external objects, it must internally rely on the manas as its defiled faculty before it can arise. Hence the treatise quoted above says: 'Relying precisely on this continuous consciousness, down to being named the manovijñāna.' There is no separate manas listed in that treatise or in this sūtra, and the Laṅkāvatāra is also like this; this is because the seventh calculates the internal as self, combining with the transforming mark, and calculates the external as what belongs to self, combining with the consciousness of things. If one did not connect the preceding and bring along the succeeding, then the meaning of showing the mental factors arising in succession would not be apt.