The Regulatory Scope of Manas over Rūpa-kāya

The black box refers to the five subtle material faculties within the brain, including the visual perception center, auditory perception center, olfactory perception center, tactile perception center, motor nervous system, and language center; it encompasses parts of the cerebrum, telencephalon, brainstem, cerebellum, etc., but excludes the cerebral cortex. The cerebral cortex is solely regulated by the manas (the seventh consciousness). The manas governs all brain activities, which even the sixth consciousness (mano-vijñāna) does not fully comprehend. Therefore, the scope of the sixth consciousness's activities is narrower than that of the manas.

All changes, flows, and movements of the physical body fall within the domain of the saṃskāra skandha (the aggregate of mental formations) and are directly regulated by the manas, with the participation of body consciousness (kāya-vijñāna) and the sixth consciousness. However, conscious thought, analysis, and control are not necessarily involved. The manas clings to these activities as self and what belongs to self, constituting the view of self (satkāya-dṛṣṭi). Nevertheless, the autonomous activities of the physical body, such as the functioning of internal organs, heartbeat, pulse, gastrointestinal peristalsis, cellular metabolism, nail and hair growth, etc., are not regulated by the sixth consciousness or the manas. These are activities through which the ālaya-vijñāna (storehouse consciousness) sustains the living being according to karmic seeds (bīja) and karmic conditions.

External bodily activities necessarily involve the sixth consciousness and body consciousness. However, on familiar routes, the manas can lead the sixth consciousness and body consciousness through the path without the need for conscious deliberation or direction. If the route is unfamiliar, the manas must rely on the analytical guidance of the sixth consciousness to lead the sixth consciousness and body consciousness through the path. Cellular metabolism, changes in tissue structure, and the growth and transformation of muscles, bones, and teeth are not controlled by the manas or the sixth consciousness. They change according to karmic seeds and karmic conditions.