成唯識論述記 7.409

7.409

述曰：此第二解。又意識於色等能明了取，即雖現量，異於眼等識，彼不能明了分別深取境之相故，故意助五，非無用也。既爾，即是五取不明假意明取，何故無二眼識俱明取也？答：不然。此中意起，言有二義：一、明了；二、助五。設意有明了，如定心等取，不能引五故，不可為例，以意識能明了，取復助五生。

The Commentary states: This is the second explanation. Furthermore, the mano-vijñāna is able to grasp clearly with respect to form and so forth; that is, although it is direct perception (pratyakṣa), it differs from the eye-vijñāna and so forth, because those [five] cannot clearly discriminate and deeply grasp the characteristics of the cognitive object. Therefore the manas assists the five, and it is not without function. If that is so, then the five grasp unclearly and rely on the manas to grasp clearly; why then do two eye-vijñānas not co-arise to grasp clearly together? We answer: That is not so. In this context, the arising of the manas has two functions: first, clarity; second, assisting the five. Even if the manas possesses clarity, as when grasping in a concentrated mind (samāhita-citta) and so forth, it cannot induce the five, so it cannot serve as a parallel; for the mano-vijñāna can both grasp clearly and additionally assist the arising of the five.