Is the Dharma That Sentient Beings Ascertain in Their Minds Necessarily Correct?

Not so. If it were so, the Buddha would not have told sentient beings: "Your mind is not to be believed; only after attaining the fruit of arhatship can your mind be believed." Here, the fruit of arhatship refers to the ultimate fruit of the Small Vehicle, the fourth fruit; the third fruit still falls a bit short. Confirmation means that the manas definitively affirms and accepts something, forming an uninterrupted attention (manaskāra) that penetrates to the marrow, unshakable, and also unfathomably deep. For example, the view of self (satkāya-dṛṣṭi): sentient beings' manas confirms this, deeply rooted and unshakable—this is called self-grasping (ātma-grāha).

To have utmost faith in one's own mind without doubt, to be extremely certain of oneself—this is the manas's confirmation. Yet the confirmations of ordinary sentient beings (pṛthagjana) carry great faults and great perils of birth-and-death. For instance, ordinary beings all confirm that the five aggregates (pañca-skandha) are the self; such a confirmation is a wrong view/false view (mithyā-dṛṣṭi), not right view. Since beginningless kalpas, ordinary sentient beings have always confirmed that their own views are correct and without error, yet throughout beginningless kalpas they have transmigrated through birth and death because of erroneous and inverted views, receiving all manner of evil retributions and bitter retributions.

"Your mind is not to be believed"—the Buddha used this not only to admonish ordinary sentient beings, but also to admonish those of the first, second, and third fruits, because before the fourth fruit, one's cognition of the emptiness of the world of the five aggregates is still not adequate or ultimate; the view of self has not been fully eradicated from one's thoughts and concepts, and self-grasping remains. The arhat of the fourth fruit has completely eradicated the view of self, is thoroughly empty, and has eliminated self-grasping and the conceit "I am"; only then is the concept of emptiness pure and can one's mind be believed. This concept of emptiness is thorough and ultimate only within the scope of the Small Vehicle dharma; compared with the Great Vehicle dharma, it is still very incomplete and non-ultimate.

Therefore, whether or not an ordinary being has attained a fruit, generally speaking, his wisdom is insufficient for self-examination. First, his time spent cultivating is short and his experience insufficient; second, he has seen and heard little and has nothing to compare against, so misjudgment and erroneous judgment come easily. Moreover, because there is a self in his mind and he cannot transcend attachment and affection, he will show favoritism toward and overestimate himself, easily resulting in false enlightenment and false speech, and in the end, cause and effect never fail.