The Regulation of Life Activities by the Manas

All movements, flows, and activities of the physical body belong to the scope of the aggregate of formations (saṃskāra); they are directly regulated by the manas, with the body consciousness and mind consciousness participating, but not necessarily involving the mind consciousness's deliberative analysis and directive function. When the manas grasps these activities as self and what belongs to self, that is the self-view (ātma-dṛṣṭi). External activities of the body necessarily involve the participation of the mind consciousness and body consciousness. For example, when walking along a familiar stretch of road, without the mind consciousness deliberating and directing, the manas can lead the mind consciousness and body consciousness to complete that stretch of road; if the road is unfamiliar, the manas must rely on the mind consciousness's deliberative analysis and guidance in order to lead the mind consciousness and body consciousness to complete that stretch of road.

However, the autonomous activities of the physical body's organism—such as the activities of the internal organs, the heartbeat, pulse, gastrointestinal peristalsis, the metabolism of cells and tissues, the growth of hair and nails, changes in tissue structure, the growth and transformation of muscles and bones, and so on—are not regulated by the mind consciousness or the manas. They all undergo change in accordance with karmic seeds and karmic conditions; they are the sustaining activities carried out upon the living organism by the tathāgatagarbha in accordance with karmic seeds and karmic conditions.