The Scope of the Manas's Regulation of the Physical Body

The black box refers to the five supreme faculties (indriya) in the brain, including the visual perception area, the auditory perception area, the olfactory perception area, the tactile perception area, the motor central nervous system, and the language central nervous system; it includes part of the brain, the telencephalon, the brainstem, and the cerebellum, and so on, but does not include the cerebral cortex. The cerebral cortex is regulated only by the manas; the manas is responsible for all brain activities, which even the mind consciousness does not understand. Therefore, the scope of the mind consciousness's activity is smaller than the scope of the manas's activity.

Whatever movements, flows, and activities of the material body belong to the domain of the aggregate of volitional formations, directly regulated by the manas, with the body consciousness and mind consciousness participating, but not necessarily involving the mind consciousness's deliberation, analysis, and direction. The manas grasps these activities as self and as belonging to self — this is the view of self (satkāya-dṛṣṭi). However, the autonomous activities of the body's physical organism, such as the activities of the internal organs, the heartbeat, the pulse, gastrointestinal peristalsis, the metabolism of cells and tissues, the growth of hair and nails, and so on, are not regulated by the mind consciousness or the manas; they are activities by which the tathāgatagarbha sustains the living being in accordance with karmic seeds and karmic conditions.

External activities of the body necessarily involve the participation of the mind consciousness and the body consciousness; it is only that on relatively familiar stretches of the path, the manas can lead the mind consciousness and body consciousness through that stretch without the mind consciousness's deliberation and direction. If that stretch of the path is unfamiliar, the manas must rely on the mind consciousness's deliberation and analysis for guidance in order to lead the mind consciousness and body consciousness through it. The metabolism of cells, changes in tissue structure, and the growth and changes of muscles and bones are not controlled by the manas or the mind consciousness; they all change in accordance with karmic seeds and karmic conditions.