The Wisdom of the Manas and the Deliberation of the Manas

The manas itself has no language, words, or sound-marks; it does not think by means of language and words, and when it exerts mental effort there is no sound either. Therefore the mental activities and operational characteristics of the manas are hidden and hard to observe, not easy to capture. When meditative concentration (samādhi) is insufficient, the mind is not subtle, and it becomes very difficult to observe; then misunderstandings about the manas are inevitable.  

The mind consciousness sometimes has wisdom and sometimes lacks wisdom; the manas likewise sometimes has wisdom and sometimes lacks wisdom. When the wisdom of the mind consciousness functions well, it can assist the manas in discernment and decision-making. But if the manas itself already has wisdom, it does not need the mind consciousness's wisdom to assist it, or it does not need the mind consciousness to assist with deliberation and analysis—only helping with discernment is enough. As soon as the manas discerns the coarse and subtle characteristics of a dharma, it immediately knows how to handle and deal with it. This is so when the manas itself has wisdom. When the manas lacks wisdom, the mind consciousness is needed not only to assist with discernment, but also to assist with deliberation, analysis, reasoning, and judgment; then the manas deliberates (manana) based on the mind consciousness's judgment and makes its own decision, which is not necessarily consistent with the mind consciousness's judgment—its decision may even come as a surprise to the mind consciousness.  

When the mind consciousness introspects upon its own mind, that is self-validating cognition (sva-saṃvitti-saṃvitti-bhāga); if what the mind consciousness observes is a mental thought of the manas, that is self-cognition (svasaṃvitti). But when the mind consciousness lacks wisdom, it may not be able to clearly distinguish whether it is its own mental thought or a mental thought of the manas, and will take both to be the mind consciousness's own thoughts. That is why many people say: "This is clearly a function of the mind consciousness—how can you say it is a function of the manas?" In fact, it is because their own mind consciousness lacks the wisdom to clearly distinguish the differences and boundaries between the mind consciousness and the manas, and lacks the wisdom of the varieties of paths. To clearly distinguish the functions of the mind consciousness and the manas is indeed extremely difficult.