The Relationship between Manas and Mind Consciousness Is Like the Relationship between Eyes and Glasses.

The relationship between the manas and the mind consciousness is like the relationship between the eyes and a pair of eyeglasses. When the eyes cannot see something clearly, they need to wear eyeglasses to assist in discernment; whatever the eyeglasses help to discern, the eyes take to be their own discernment. But some relatively coarse things that are easy to distinguish can be discerned by the eyes themselves, without the help of eyeglasses—then there is no need to wear glasses, which is analogous to the mind consciousness not needing to arise. There are indeed many occasions when the eyes discern things on their own without the aid of glasses; likewise, the dharmas that the manas can discern on its own are truly numerous, and the mind consciousness does not know about this portion of content. But not knowing about it does not mean the manas has not discerned those dharmas.

Therefore, over all dharmas, the manas holds absolute initiative and control. All dharmas must serve the manas and be used by the manas—including the mind consciousness itself.

If the eyes have grime on them, can washing only the eyeglasses guarantee that the eyes will discern things clearly? The manas has had ignorance (avidyā) since beginningless kalpas, and because of this ignorance it holds various wrong views (mithyā-dṛṣṭi). If we only let the mind consciousness eradicate the view of self (satkāya-dṛṣṭi) and attain enlightenment to see the mind and see its nature, only removing the ignorance of the mind consciousness, can that guarantee that the false master of all dharmas has a pure mind-ground? Can it guarantee that the master will handle and treat all dharmas with wisdom?

When one cannot see clearly, should one treat the eyes or repair the eyeglasses? Many people who study Buddhism remain only at the stage of repairing the eyeglasses, unwilling or unable to go a step further and treat the eyes. After washing the eyeglasses, one must also wash the eyes; otherwise one still cannot see things clearly. When the mind consciousness has become clear, the manas must also be made clear; otherwise one remains foolish and deluded.

Since the manas and the mind consciousness stand in such a relationship, the mental activities and mental nature of sentient beings mainly refer to the mental activities and mental nature of the manas. The ignorance of the manas, the clarity of the manas, and the mental factors (caittas) of the manas are extremely important. If the mental factors of the manas were free of ignorance—if they were all clear—then there would be no need to cultivate any further, and the mind consciousness would no longer have much of a role to play: the old ox would have arrived home, and the herdboy, his task completed, could rest.