Turning the Awareness Back to the Source is the Dharma Gate of Perfect Penetration of Manas (Manas Training Chapter)

Original text from Volume Five of the Śūraṅgama Sūtra: Then, Aniruddha arose from his seat, prostrated at the Buddha's feet, and addressed the Buddha, saying: "When I first left the household life, I was often fond of sleep. The Tathāgata reproached me, calling me one of the animal kind. Hearing the Buddha's reproach, I wept in self-reproach. For seven days and nights I did not sleep, and I lost the sight of both eyes. The World-Honored One then taught me the 'Vajra-like Samādhi of Delight in Illuminating Perception.' Not relying on the eyes, I contemplate and perceive the ten directions, utterly clear and vivid, as if looking at a fruit in my palm. The Tathāgata confirmed my attainment of Arhatship. Now, the Buddha asks about perfect penetration. According to my realization, revolving the faculty of sight back to its source is foremost."

Explanation: Aniruddha began his practice from the eye faculty. His insight from cultivation was "revolving the faculty of sight back to its source." "Revolving" means turning around, reversing – turning the eye faculty's seeing, which was originally directed outward, back inward, following the source of seeing, that is, returning to the fundamental root. Originally, seeing perceived form externally, outside the body and mind. Now, one must reverse this to see the fundamental root of that which can see. What is this fundamental root? It is the source that gives rise to the function of seeing. What guides and determines the seeing of the eye faculty? First, it is the mental faculty (manas); second, it is the eighth consciousness (ālaya-vijñāna). The most ultimate point is the eighth consciousness.

Returning to the mental faculty is the stage of a great Arhat. Returning to the eighth consciousness is the stage of a great Bodhisattva. From the perspective of the conventional world, the mental faculty has the function of perceiving all dharmas, including the perception of the inner and outer six sense-object realms. However, due to ignorance, the mental faculty's function of perceiving dharmas is restricted, forcing it to rely on the six consciousnesses perceiving through the five sense faculties. If ignorance is removed, restoring the mental faculty's maximum function, then one need not rely on the six consciousnesses perceiving outward through the five sense faculties. The mental faculty alone can perceive dharmas, allowing the five sense faculties to rest and the six consciousnesses to cease.

Aniruddha, through cultivating the "Vajra-like Samādhi of Delight in Illuminating Perception" taught by the World-Honored One, trained in using the mental faculty to perceive dharmas, turning the seeing inward without relying on the eye faculty. As a result, he could perceive the worlds of the ten directions, utterly clear and vivid, truly and distinctly, just like looking at a fruit in his own hand. "Revolving the faculty of sight back to its source" is indeed the perfect penetration of the mental faculty. Who said the mental faculty cannot perceive the objects of the five senses? The mental faculty of the great Arhat Aniruddha could perceive the worlds of the ten directions, utterly clear and vivid – forms, sounds, smells, tastes, touches, and mental objects, nothing unseen. He attained samādhi through the mental faculty, rendering the mental consciousness (mano-vijñāna) unnecessary. Therefore, the notion that the mental consciousness is essential for realizing the fruit is the greatest absurdity.