Does something not exist just because the mind consciousness cannot observe it?

The deliberation (manana) of the mind consciousness is manifest and easy to observe, whereas the deliberation of the manas is hidden and not easy to observe. Because the mind consciousness has a relatively strong power of introspection, the solitary mental consciousness can observe some of the running modes of activity of the mental consciousness accompanying the five sense consciousnesses (pañcavijñāna-sahagata-manovijñāna) and of the solitary mental consciousness itself, but it cannot observe them all, because the mind consciousness has not yet accomplished the transformation of 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 mental consciousness is obstructed by afflictions, lacks sufficient meditative concentration (samādhi), and has not transformed consciousness into wisdom, it cannot observe the running modes of activity of the manas. This is why it must be said that the deliberation of the manas is hidden. In fact, for the Buddha and for bodhisattvas who have transformed consciousness into wisdom, the modes of activity of the manas are still easy to observe.

Whether it is hidden or manifest depends entirely on the person, not on the mind consciousness or the manas themselves. The manas also has self-validating cognition (sva-saṃvitti-saṃvitti-bhāga) and possesses a weak power of introspection, capable of observing the manas' own modes of activity; but the manas cannot express this, so the mind consciousness—which is what we call "we"—does not know. Since the mind consciousness does not know the modes of activity of the manas, whether the manas' power of introspection is strong or weak, the mind consciousness still does not know.

When it comes to 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 might just as well say the Earth is motionless and static. There is nothing wrong with saying so, but it does not accord with the facts.

How many facts and truths can the mind consciousness of an ordinary person actually observe? Not very many. Ignorance is too abundant and too thick, the obstructions too heavy; and precisely those with the most ignorance are the least willing to admit their own ignorance and the most trusting of their own judgments. This is what is called helplessness!