大乘起信論略述 1.148

1.148

Treatise: It is named mental consciousness... consciousness of discriminating phenomenal objects.
Commentary: This establishes its name. As for being named "mental consciousness": since it conditions the six dusts, it should be called the six consciousnesses; yet here, in terms of the meaning of a single mental consciousness, it does not separately bring out the five consciousnesses of the eye and so on, but is only named "mental consciousness." Therefore the Mahāparinirvāṇa-sūtra says: "For example, a single consciousness is discriminatorily explained as six." Because this mental consciousness relies on the six sense-bases to separately apprehend the six dusts, it is said to "separate"; and because it can discriminate past and future, internal and external, various phenomenal marks, it is further named the "consciousness of discriminating phenomenal objects".