Awakening to the Way through the manas yields the deepest wisdom

The Buddha said that the manas silently contains all dharmas; "silently contains" is equivalent to universally cognizing them. Most importantly, the eighth consciousness cannot manifest dharmas on its own, nor can it hold and sustain dharmas on its own; it must have the manas. Otherwise, the eighth consciousness in nirvāṇa without remainder would also be able to manifest dharmas and hold dharmas, and then it would not be tranquil. The manas is the fundamental driving force behind the arising of the dharmas of the three realms; the arising of any dharma is propelled by the manas, and the eighth consciousness cannot operate alone. This shows that on all dharmas there is not only the operation of the eighth consciousness but also the operation of the manas; therefore, the manas can cognize all dharmas, and no dharma is without the manas. 

Even the karmic retribution that the manas is unwilling to undergo, and the karmic seeds that the manas is unwilling to engage with, are manifested by the eighth consciousness only because of the manas' condition. If it were not so, arhats still have karmic seeds, and in nirvāṇa without remainder, the eighth consciousness should manifest those karmic seeds; if they could be manifested, it would no longer be the state of nirvāṇa without remainder, and the eighth consciousness would be engaging in conditioned karma.

The mind consciousness cannot have any single function or role of its own; it is always bound together with the manas, and everything is the result of the manas' assistance. The mind consciousness cannot operate independently apart from the manas. Therefore, the function of the manas is extremely prominent and important.

The process by which a person's mind consciousness is activated is this: the manas first gives rise to a thought; after the mental engagement (manaskāra), the volition (cetanā) mental factor appears, and then the mind consciousness produces thoughts and ideas. When a thought arises, it is always the manas that first gives rise to it, and then the mind consciousness's thought emerges. Without the manas's thought, there is no thought of the mind consciousness. In the practice of investigating the huatou, in the end it is still a matter of tethering the manas to the huatou, never forgetting it for a single thought, from morning to night; only then can one break through the investigation—and this too is the result of the manas giving rise to thoughts. The manas giving rise to a thought is precisely mental engagement (manaskāra). Giving rise to a thought is mental engagement; the words are merely different.

In fact, the six consciousnesses and the eighth consciousness have always been performing a two-person act together; thus one can discover the traces of the eighth consciousness in the bodily, verbal, and mental actions of the six consciousnesses. Likewise, the manas and the eighth consciousness are also performing a two-person act together; thus one can also find the traces of the eighth consciousness in the operations of the manas—in the manas's mental engagement, contact, feeling, perception, and volition, and in all the manas's functions of decision-making and exercising mastery. Therefore, awakening to the Way through the manas is deeper, more direct, more thorough, and more ultimate, and the wisdom thus aroused is the deepest.