External and Internal Feelings in the Mahāsatipaṭṭhāna Sutta

In the Great Mindfulness Sūtra (Mahāsatipaṭṭhāna Sūtra), when the Buddha taught the contemplation of feeling, He spoke of two kinds of feeling: inner feeling and outer feeling. Outer feeling refers to the feeling of the mind consciousness that is easy to observe, especially the feeling of the mind consciousness with respect to the objects of the six sense-dusts; inner feeling refers to the feeling of the manas, which is hidden more deeply and is not easy to observe. Although the vast majority of people cannot distinguish between the mind consciousness and the manas, the mental activities deep within the mind can still be perceived and observed, as long as the mind is very subtle and attentive.

When the Buddha taught the contemplation of the mind, observing the mind meant observing the afflictions of greed, hatred, and delusion in both the inner mind and the outer mind, and observing whether the inner mind and the outer mind are concentrated or scattered, expansive or limited, surpassed or unsurpassed, concentrated or unconcentrated, liberated or not liberated. This shows that the inner mind, the manas, has the afflictions of greed, hatred, and delusion, can be concentrated or unconcentrated, and can be liberated or not liberated. This proves from the Hīnayāna sūtras that the manas possesses these mental factors (caittas), even though the World-Honored One did not state it explicitly. Because the dharma of the manas is something that even Mahāyāna disciples cannot understand and realize, let alone Hīnayāna disciples being able to deeply and correctly understand the dharma of the manas, the World-Honored One had no choice but to teach the mental factors of the manas in a hidden, esoteric way.

The affliction of doubt has inner doubt and outer doubt; when severing doubt, it must be severed completely and ultimately—that is, the doubt of the manas must be severed. Therefore, the three fetters refer entirely to the fetters of the manas; only by severing the doubt of the manas are the three fetters severed. By severing greed—the greed of the manas—can the mind correspond with the devas of the form realm and be reborn in the form realm heavens. By severing hatred—certainly the hatred of the manas must be severed—can one be a person of the third fruit (anāgāmin). By severing delusion—certainly the delusion and ignorance of the manas must be severed—can one escape the three realms.

The Hīnayāna Buddhist sūtras are the easiest to understand, yet how many people can truly comprehend the Hīnayāna sūtras? Let alone the Mahāyāna sūtras—how many people can truly understand them completely? Even when attaining the fruit of arhatship, one still cannot completely "believe your own mind"; when wisdom is insufficient and the understanding of the manas is not ultimate, fully trusting it easily leads to errors.

The Buddha-dharma is not fragmented and disjointed; it must be coherent and continuous from beginning to end, with all parts mutually supporting and explaining one another. When it comes to debating the Buddha-dharma, who is qualified to debate? What qualification do those of small faculties and small wisdom have to initiate or participate in a debate?