External and Internal Sensations in the Mahāsatipaṭṭhāna Sutta

In the Mahāsatipaṭṭhāna Sutta, when the Buddha spoke of contemplating feelings, he described two types: internal feelings and external feelings. External feelings refer to the feelings of the conscious mind that are easily observable, particularly the feelings of consciousness in relation to the six sense objects. Internal feelings refer to the deeply hidden feelings of the manas (mental faculty) that are difficult to observe. Although most people cannot distinguish between consciousness and manas, the subtle mental activities within the depths of the mind can still be perceived and observed, provided the mind is sufficiently refined.

When the Buddha spoke of contemplating the mind, he instructed to observe the afflictions of greed, hatred, and delusion in the internal mind and external mind, and to observe the focused and scattered states, the vast and narrow states, the superior and unsurpassable states, the concentrated and unconcentrated states, and the liberated and unliberated states of the internal and external mind. This indicates that the internal mind (manas) possesses afflictions such as greed, hatred, and delusion, as well as states of concentration and non-concentration, liberation and non-liberation. This, from the Theravāda scriptures, proves that manas possesses these mental factors, although the World-Honored One did not explicitly state it. Because the nature of manas is beyond the comprehension and realization of even Mahāyāna disciples, let alone Theravāda disciples who could deeply and correctly understand it, the World-Honored One had no choice but to speak of the mental factors of manas in an implicit manner.

Doubt as an affliction includes internal doubt and external doubt. To eradicate doubt completely, one must eliminate the doubt of manas. Therefore, the three fetters entirely refer to the fetters of manas. Only by severing the doubt of manas can one break the three fetters. Severing greed—eliminating the greed of manas—enables the mind to resonate with the Brahmā heavens, allowing rebirth in the form realm. Eliminating hatred—specifically eradicating the hatred of manas—defines the attainment of the third fruit (anāgāmi). Eradicating delusion—specifically eliminating the delusion and ignorance of manas—enables liberation from the three realms.

The Theravāda sutras are the easiest to understand, yet how many people can truly comprehend them? How much less so the Mahāyāna sutras—how many can fully and truly understand them? Even an arhat cannot place complete trust in one's own mind; wisdom remains insufficient, and the mind is not yet ultimate. Placing full trust in it easily leads to errors.

The Buddha Dharma is not fragmented; it is invariably coherent and continuous from beginning to end, with all parts mutually supporting and illuminating one another. Regarding debates on the Buddha Dharma, who is truly qualified to engage in such debates? What qualifications do those with shallow roots and meager wisdom possess to initiate or participate in debates?