What is the realm of realization and enlightenment?

The first line of the Heart Sutra says: When Avalokiteśvara Bodhisattva practiced the profound prajñā-pāramitā, he illuminated and saw that the five aggregates (pañcaskandha) are all empty, and thereby crossed over all suffering and distress. Practicing the profound prajñā-pāramitā and illuminating the emptiness of the five aggregates means that at the very moment one realizes the tathāgatagarbha endowed with prajñā wisdom, the mind becomes empty. The key word here is "practiced," which means investigating through Chan the meaning and principles of prajñā. "Profound" refers to two things: one is depth of meditative concentration (samādhi), and the other is depth of the wisdom of investigation, with a clear direction. Under the precondition of this profundity, the sixth and seventh consciousnesses give rise to great wisdom, which wisdom illuminates the real characteristic of the dharmadhātu, realizing that all dharmas within the five aggregates are manifested by the prajñā mind, the tathāgatagarbha, and that the essential nature of the five aggregates is empty—false appearances, illusory forms.

In this way, deep in one's heart one knows that the five aggregates are not real, and thus there is no suffering; in an instant one crosses over all suffering and distress. All suffering and distress are conjured up by the tathāgatagarbha; they are false appearances, unreal. Having thus illuminated and seen that the five aggregates are all empty, the mind becomes empty and non-active, and afflictions are severed. This is the merit and benefit of attaining the Mahāyāna path of seeing by realizing the tathāgatagarbha. This is the manas attaining the path of seeing, the manas realizing the samādhi state of the tathāgatagarbha, complete in both samādhi and wisdom, the equal cultivation of Samādhi and Prajñā. The so-called "illuminating and seeing" means sudden enlightenment—there is no time or effort of gradually understanding through pondering, analyzing, and deliberating; one knows or one does not know, without hesitation or ambiguity.

After thus illuminating and seeing that the five aggregates are all empty, is it still necessary to separately undertake the transformation of the basis as tathāgatagarbha for it to count as realization and enlightenment? Not at all. This is genuine, unambiguous realization and sudden enlightenment, not the kind of gradual interpretive awakening that is gradually clarified through analysis and inference. One has thus already entered the gate of the Mahāyāna and obtained genuine merit and benefit. If, however, one uses the mind consciousness to reason, ponder, and guess at a tathāgatagarbha, such guessing and inference carry no merit or benefit whatsoever, and so one must slowly undertake the transformation of the basis. Yet no matter how hard the mind consciousness strives at the transformation, if the manas has not realized it, the transformation of the basis cannot succeed. Consequently, a huge mess of problems remains unresolvable—afflictions are still afflictions, ignorance is still ignorance.

 This is like those who take meditative concentration as Chan: they cultivate a samādhi in which not a single thought arises, and take this to be the thought-free state of the true mind, thereby mistaking the false for the true. But after emerging from concentration, deluded thoughts appear again. Because they fear in their hearts that the true mind will vanish, they keep cultivating concentration, striving to remain in meditative concentration for as long as possible, trying not to emerge from it, in order to preserve and safeguard the state of concentration and ensure the true mind is not lost—calling this, in fine-sounding terms, "preserving and safeguarding." However, the state of concentration will eventually disappear, and one must eventually emerge from concentration. Even if one did not emerge from concentration for countless kalpas, the state of concentration is still not the true mind, the self-nature. If one has truly awakened, what is there to preserve and safeguard? If one has truly realized the true mind, what is there left to transform? It is right here and now; in this very moment the mind is empty and pure. Like the carp leaping over the Dragon Gate—having leapt over and become a dragon, would it still fear leaping back and turning into a carp again? Only if one has never actually leapt over the Dragon Gate, with a heart trembling in fear, anxious about gain and loss, would one need to preserve, safeguard, and transform.