What does it mean that the manas internally grasps the Ālayavijñāna as self?

This means that the manas grasps the functions and operations of the Ālayavijñāna as its own functions and operations, without knowing that these are the functions and operations of the Ālayavijñāna. Following along with the dharmas perceived by the Ālayavijñāna, it regards these dharmas as self and belonging to self, not knowing that they are produced by the Ālayavijñāna, belong to the Ālayavijñāna, and in essence are all of the nature of the Ālayavijñāna. Therefore, the manas craves the functions and operations of the Ālayavijñāna, delights in the functions and operations of the Ālayavijñāna, takes pleasure in the functions and operations of the Ālayavijñāna, and grasps at the functions and operations of the Ālayavijñāna. Because of these graspings and craving attachments, the manas is bound and cannot attain liberation, and thus there is birth and death that cannot be abandoned. The manas fundamentally does not know what dharma the Ālayavijñāna is, so it is not grasping at the Ālayavijñāna itself; rather, it mistakenly believes that all the functions produced by the Ālayavijñāna are its own functions and that all dharmas belong to itself, and thereby grasping arises.

What are the functions and operations of the Ālayavijñāna? Nothing other than the functions and operations of the five aggregates and eighteen realms, nothing other than the functions and operations of all worldly dharmas. The manas takes all these functions and operations as self and what belongs to self. This misunderstanding only begins to be gradually dispelled after one realizes the Ālayavijñāna. When the manas realizes the Ālayavijñāna, it will, together with the mind consciousness, observe that the functions and operations of the five aggregates and eighteen realms are all produced by the Ālayavijñāna and are the functions and operations of the Ālayavijñāna, not the functions and operations of the manas-self, and thus it gradually eradicates the grasping at self. Then, as it successively realizes that all other dharmas are likewise the functions and operations of the Ālayavijñāna and not the functions and operations of the manas-self, it gradually eradicates the grasping at dharmas. Ignorance is gradually exhausted, one accomplishes the supreme nirvāṇa, and attains great liberation.

Animals all have grasping at self and grasping at dharmas—which of them can know there is an Ālayavijñāna? They merely take those functions produced by the Ālayavijñāna and those dharmas it gives rise to as their own. What the manas grasps is only those dharmas produced by the Ālayavijñāna—how could it be grasping at the Ālayavijñāna itself? Studying the Dharma is not about dissecting words; one cannot go around in circles with the literal text, but must deeply engage in contemplative practice (vipaśyanā-caryā) on its profound meaning and ultimate meaning. Most people's study of the Dharma consists only of shallow deliberation by the consciousness; they never cultivate meditative concentration to think deeply and contemplate. That is why so many people who cultivate and study the Small Vehicle's teachings on suffering, emptiness, impermanence, and non-self end up drawing the conclusion that "the five aggregates are not the eighth consciousness yet are not different from the eighth consciousness"—a conclusion that is not even logically coherent. What ordinary being would have the notion that the five aggregates are the eighth consciousness? Anyone who has this notion is no longer an ordinary being, and would not need to engage in contemplative practice to eradicate the view of self (satkāya-dṛṣṭi-prahāṇa) or to personally realize the eighth consciousness at all.