Do dharmas that consciousness cannot observe not exist?

The deliberation (manasikāra) of the mind consciousness is overt and easy to observe, whereas the deliberation of the manas is covert and not easy to observe. Because the mind consciousness has a relatively strong power of introspection (pratyavekṣā-bala), the solitary consciousness (mano-vijñāna-eka-citta) can observe some of the operational characteristics of the consciousness accompanied by the five senses (pañca-sahagata-mano-vijñāna) and of the solitary consciousness itself, but it cannot observe them all, because the mind consciousness has not transformed consciousness into wisdom. The Buddha can observe them all, and the wisdom of the varieties of paths of bodhisattvas who have attained the bhūmis can observe most of them.

However, when the solitary consciousness is obscured by afflictions, lacks sufficient meditative concentration (samādhi), and has not transformed consciousness into wisdom, it cannot observe the operational characteristics of the manas. That is why it must be said that the deliberation of the manas is covert. In fact, for the Buddha and for bodhisattvas who have transformed consciousness into wisdom, the operational characteristics of the manas are still easy to observe.

Whether something is covert or overt depends entirely on the person, not on the mind consciousness or the manas themselves. The manas also has self-validating cognition (svasaṃvedana) and possesses a weak power of introspection, capable of observing the manas' own operational characteristics; but the manas cannot express them, so the mind consciousness (that is, what we call "we") does not know. Since the mind consciousness does not know the operational characteristics of the manas, whether the manas' power of introspection is strong or weak, the mind consciousness still does not know.

Regarding things the mind consciousness does not know, many people's mind consciousness habitually denies them, saying they do not exist. Then, since the mind consciousness cannot observe the Earth's revolution and rotation, one could also say the Earth is motionless and static. Saying so would not really matter, but it would not accord with the facts.

How many facts and truths can the mind consciousness of ordinary people actually observe? Not many. Ignorance is too abundant and too thick, and the obstructions are too heavy. Yet the more ignorant a person is, the more they refuse to admit their own ignorance and the more they trust their own judgments—this is what is called helplessness!