The Meaning of the "Staring-Induced Fatigue Phenomenon" in the Tathāgatagarbha as Expounded in the Śūraṅgama Sūtra

The phenomenon of exertion and contact pertaining to the Tathāgatagarbha is caused by the manas (mind faculty). The essential nature of the Tathāgatagarbha itself does not possess exertion, contact, or the phenomenon of exertion and contact, because it is devoid of any inclination toward the dharmas (phenomena) of the three realms. The Tathāgatagarbha, whose intrinsic nature is quiescent extinction, continuously gives rise to various dharmas as the manas ceaselessly grasps and attaches. Consequently, it inevitably uses the eye to perceive form, uses the ear to hear sound, uses the nose to smell scents, uses the tongue to know taste, uses the body to feel contact, and uses the consciousness to know dharmas. In this way, the phenomenon of exertion and contact at the six sense bases arises. 

If the manas does not grasp and attach to any dharmas, the Tathāgatagarbha remains in a state of quiescent extinction. It does not give rise to any dharmas, and thus the functions and activities of the six sense bases do not manifest. When deluded dharmas do not arise, the Tathāgatagarbha abides in true immovability, profoundly still and quiescent. Originally, the Tathāgatagarbha gives rise to no dharma whatsoever and remains unmoved by any dharmas. However, when karmic seeds ripen due to conditions, deluded movement inevitably occurs, and dharmas must necessarily be born. Once dharmas are born, exertion and contact occur; this is compelled by the manas. Yet the Tathāgatagarbha has no thought or notion of being compelled, nor is it aware of being compelled. It merely acts spontaneously in accordance with conditions, without entertaining other thoughts.