大乘起信論義記別記 1.31

1.31

Eighteenth: Question: Among the three subtle marks and six coarse marks, why is manas not mentioned? Answer: Because the meaning would be inconvenient. How so? Because fundamental ignorance stirs that tathatā and forms the three subtle marks, which are called the ālayavijñāna. Manas does not have this meaning, so it is not discussed. Moreover, because of "conditions of objects," stirring that ocean of mind gives rise to the six coarse marks, which are called the manovijñāna. Manas does not have this meaning of arising from external objects, so it is not discussed. Although it is not mentioned, the meaning is already present. How is this known? The Yogācārabhūmi says: "When the ālayavijñāna arises, it must be concordant with two consciousnesses." Therefore, in speaking of the ālayavijñāna of the three subtle marks, grasping concordant with manas is already present. Moreover, for the manovijñāna to be able to condition external objects, it must internally rely on manas; therefore, in speaking of the manovijñāna of the six coarse marks, it already has manas as its supporting faculty. Therefore, although not mentioned, in reality it exists.