Introduction

Nirvāṇa (Pali nibbāna) in sutra is "bhavanirodha nibbānam" (The cessation of becoming means Nirvāna). Nirvāna in sūtra is never conceived of as a place, but the antinomy of samsāra (see below) which itself is synonymous with ignorance (avidyā, Pāli avijjā). “This said:

Undefinable nature

Gautama Buddha sometimes refers to nirvāna as amṛta / amata ("Immortality" Im-Mortalis, A-mata):

What Nirvana is Not

Nirvana is the complete realization of the middle way (majjhena dha"mma"m deseti) and is neither the extremist view of nihilism(Pali: Ucchedavaada), nor eternalism (Pali: Sassatavaada), nor the monism of "oneness with Brahman" (as taught in Hinduism).

Nirvāna and Samsāra

In Mahāyāna Buddhism, calling nirvāna the "opposite" of samsāra or implying that it is apart from samsāra is doctrinally problematic. According to early Mahāyāna Buddhism, they can be considered to be two aspects of the same perceived reality. By the time of Nāgārjuna, there are teachings of the identity of nirvāna and saṃsāra. However, even here it is assumed that the natural man suffers from at the very least a confusion regarding the nature of samsāra.

Nirvana in Buddhist Commentaries

Sarvastivàdin commentary, Abhidharma-mahavibhàsa-sàstra, gives the complete context of the possible meanings from its sanskrit roots:

Nirvāna in the Mahāparinirvāna Sūtra

The nature of Nirvana assumes a differently aspected Mahayana focus in what alleges to be the final of all Mahayana sutras, allegedly delivered by the Buddha on his last day of life on earth - the Mahaparinirvana Sutra or Nirvana Sutra. Here, as well as in a number of linked "tathagatagarbha" sutras, in which the Tathagatagarbha is equated with the Buddha's eternal Self or eternal nature, Nirvana is spoken of by the Mahayana Buddha in very "cataphatic", positive terms. Nirvana, or "Great Nirvāna", is indicated to be the sphere or domain (vishaya) of the True Self. It is seen as the state which constitutes the attainment of what is "Eternal, the Self, Bliss, and the Pure". Mahā-nirvāna ("Great Nirvana") thus becomes equivalent to the ineffable, unshakeable, blissful, all-pervading and deathless Selfhood of the Buddha himself - a mystery which no words can adequately reach and which, according to the Nirvana Sutra, can only be fully known by an Awakened Being - a perfect Buddha - directly.

Quotations

• Gautama Buddha:
  • "Nirvana is the highest happiness." [Dp 204]
  • "Where there is nothing; where naught is grasped, there is the Isle of No-Beyond. Nirvāṇa do I call it -- the utter extinction of aging and dying."
  • "There is, monks, an unborn -- unbecome -- unmade -- unfabricated. If there were not that unborn -- unbecome -- unmade -- unfabricated, there would not be the case that emancipation from the born -- become -- made -- fabricated would be discerned. But precisely because there is an unborn -- unbecome -- unmade -- unfabricated, emancipation from the born -- become -- made -- fabricated is discerned." [Udana VIII.3]
  • This said: ‘the liberated mind/will (citta) which does not cling’ means Nibbāna” [MN2-Att. 4.68]
  • “'The subjugation of becoming means Nirvana'; this means the subjugation of the five aggregates means Nirvana.” [SN-Att. 2.123]
  • "Parinibbuto thitatto" -"Parinirvana is to be fixed in the Soul" [Sn 372]

• Said immediately after the physical death of Gotama Buddha wherein his mind (citta) is =parinirvana=the essence of liberation:
  • [DN 2.157] “No longer with (subsists by) in-breath nor out-breath, so is him (Gotama) who is steadfast in mind (citta), inherently quelled from all desires the mighty sage has passed beyond. With mind (citta) limitless (Brahman) he no longer bears sensations; illumined and unbound (nibbana), his mind (citta) is definitely (ahu) liberated.”
  • [SN 3.45] “The mind (citta) being so liberated and arisen from defilements, one is fixed in the Soul as liberation, one is quelled in fixation upon the Soul. Quelled in the Soul one is unshakable. So being unshakable, the very Soul is thoroughly unbound (parinirvana).”

• Sutta Nipāta, tr. Rune Johansson:
  • accī yathā vātavegena khitto
    atthaṁ paleti na upeti sankhaṁ
    evaṁ muni nāmakāyā kimutto
    atthaṁ paleti na upeti sankhaṁ
  • atthan gatassa na pamāṇam atthi
    ynea naṁ vajju taṁ tassan atthi
    sabbesu dhammesu samūhatesu
    samūhatā vādapathāpi sabbe
    
  • Like a flame that has been blown out by a strong wind goes to rest and cannot be defined, just so the sage who is freed from name and body goes to rest and cannot be defined.
    For him who has gone to rest there is no measure by means of which one could describe him; that is not for him. When all (dharmas) have gone, all signs of recognition have also gone.
• Venerable Sariputta:
  • The destruction of greed, hatred and delusion is Nirvana.