Taking the knowing of mind consciousness as knowing is precisely ignorance.

What does the self-validating cognition (svasaṃvedana) of each consciousness mean? The object-aspect (nimitta) that each consciousness self-cognizes—do you know what its content is? For example, the eighth consciousness has a perceiving-aspect (darśana-bhāga), which is the ability to see; the object-aspect of the eighth consciousness is what the eighth consciousness perceives, for example, seeds; the self-cognition (svasaṃvitti) of the eighth consciousness is that the eighth consciousness itself has perceived the object-aspect seeds, knowing and discerning the object-aspect seeds; the self-validating cognition (svasaṃvedana) of the eighth consciousness is that the eighth consciousness has verified and realized its own self-cognition, knowing that it has discerned the object-aspect seeds, knowing that it has completed the discernment of the object-aspect seeds, knowing that it has discerned the object-aspect seeds. Whatever the eighth consciousness has done, He Himself is clear about it.

But are we clear that the eighth consciousness has discerned the object-aspect seeds? We are not clear. The eighth consciousness does not know on behalf of the mind consciousness; what the mind consciousness does not know does not mean other consciousnesses do not know. One cannot use the mind consciousness's not-knowing to substitute for the knowing of other consciousnesses. If the eighth consciousness is represented by A and the mind consciousness by B, the dharmas that A knows are not necessarily known by B; that B does not know does not mean A does not know. A's self-validating cognition does not represent B's self-validating cognition; that B is not clear about the object-aspect that A has realized does not mean A has not realized it, nor does it mean A does not know.

The knowing of sentient beings is mostly based on the knowing of the mind consciousness; what the mind consciousness does not know, they say "I don't know," saying that a certain matter did not happen, that it does not exist. In fact, the seventh consciousness (manas) knows that a certain matter happened, knows that certain matter. But the seventh consciousness has no function of language and words, cannot express itself, and has no way to make the mind consciousness know. The mind consciousness then feels that what it does not know does not exist, and that other consciousnesses likewise do not know it either. Making such a determination is extremely arbitrary and unreasonable.

To what degree is the mind consciousness of ordinary sentient beings arbitrary? The mind consciousness itself cannot realize the manas and cannot observe the manas, so it refuses to acknowledge the self-cognition and self-validating cognition of the manas. The manas has an introspective nature (pratyavekṣā-lakṣaṇa) toward itself, has the power of introspection (pratyavekṣā-bala), and can introspect its own discernment; the mind consciousness does not know this and cannot observe it, yet says the manas has no power of introspection, no self-validating cognition, and lacks even certain self-cognitions. When the mind consciousness thinks this way, it precisely demonstrates its own foolishness, ignorance, and dullness—how little and how shallow what it knows is, how many misunderstandings it has—and it does not realize this itself. The Buddha said: Take heed not to believe your mind; take heed not to believe your mind; your mind is not to be believed. Why? Because ignorance is deep and heavy.