Commentary on the Sūtra of the Collection of the Father and Son (151)

What is nirvāṇa?

The path to nirvāṇa should be walked in this way. And the initial basis upon which nirvāṇa depends is certainly the one true dharma realm—the dharma of the ālayavijñāna. Without the ālayavijñāna, there would be no four kinds of nirvāṇa to speak of. It is in terms of the dharma realm of the ālayavijñāna, the tathāgatagarbha, that all dharmas are empty, tranquil, and without marks, and therefore there is no wishing or seeking. These dharma principles pervade the reaches of space; in whichever world within space, this is the same truth—all dharmas are empty. This principle applies throughout all the bounds of empty space; it is so everywhere.

Nirvāṇa is divided into four kinds: nirvāṇa with remainder (sopadhiśeṣa-nirvāṇa), nirvāṇa without remainder (nirupadhiśeṣa-nirvāṇa), the nirvāṇa of the self-natured pure mind, and non-abiding nirvāṇa (apratiṣṭhita-nirvāṇa). The nirvāṇa of the Small Vehicle is to extinguish all dharmas. Nirvāṇa is a provisional name; it refers to attaining a state that is neither arising nor ceasing. It is merely a nature or state, not a truly existent dharma.

The truly existent dharma is the tathāgatagarbha. On the substance of the tathāgatagarbha there is manifested a nature that neither arises nor ceases, a nature of immovability—this is nirvāṇa. When an arhat enters nirvāṇa without remainder, there is no arhat; only his tathāgatagarbha mind remains, abiding in a state that neither arises nor ceases. That is called nirvāṇa. So nirvāṇa is also a provisional name. Only the true mind, the mind of suchness, the tathāgatagarbha mind, is real—it is the true dharma, the actual dharma; everything else is provisional dharma.

The Buddha said the same in the Mahāparinirvāṇa Sūtra. Just as suchness (tathatā) is also a nature or state—suchness is a real and thus-like nature manifested by the ālayavijñāna, the tathāgatagarbha; it is a name. Suchness of reality is the truly existent characteristic of the tathāgatagarbha; the real nature manifested upon that truly existent characteristic, together with the nature of thusness and immovability, is true suchness. Therefore it is said that nirvāṇa practices in accord with emptiness—when emptiness is exhausted, one enters nirvāṇa without remainder. This emptiness is abiding in the realm and state of the tathāgatagarbha that neither arises nor ceases; that is called nirvāṇa.