I did a search of this thread and it doesn't look like anyone has posted this yet. Really surprising because it is really impressive and immediately relevant:
About the Nature of Nibbāna
In the Pāḷi text of the Udāna the following passage occurs relating what Buddha uttered in triumph in relation to the nature of nibbāna. This utterance has been incorporated into the Canon as the Nibbāna-paṭisaṃyutta udāna.
“Atthi, bhikkhave, tadāyatanaṃ, yattha neva pathavī, na āpo, na tejo, na vāyo, na ākāsānañcāyatanaṃ, na viññāṇañcāyatanaṃ, na ākiñcaññāyatanaṃ, na nevasaññānāsaññāyatanaṃ, nāyaṃ loko, na paraloko, na ubho candimasūriyā. Tatrāpāhaṃ, bhikkhave, neva āgatiṃ vadāmi, na gatiṃ, na ṭhitiṃ, na cutiṃ, na upapattiṃ; appatiṭṭhaṃ, appavattaṃ, anārammaṇamevetaṃ. Esevanto dukkhassā”ti. (Udāna v 71)
“Monks! There is that base that has no elements of earth, water, fire, and air. It is neither the realm of Infinity of Space, nor the realm of Infinity of Consciousness, nor the realm of Nothingness, nor the realm of Neither Perception nor Non-perception. It is neither this world nor other worlds. No moon nor sun shines there. Here, monks, I say there is no going or coming. It has no foothold or residence. It is deathless, unborn, and unformed. It has no abode. Nothing ever occurs there. It has no sense-objects. It is the end of suffering.”
Nibbāna is Real
Since nibbāna means the cessation of mind, matter, and mental formations, suggestions have often been put forward that it signifies nothing and is thus useless. However, nibbāna is absolute reality, the reality of the nullification of the activities of mind, matter, and mental formations to which the knowledge of the Path, Fruition, and reviewing (paccavekkhaṇa) is inclined. It is the mind-object to which this knowledge is directed. Buddhas, Arahants, and Noble Ones vouch for the truth of its reality. For the sake of argument, let us say that there is no nibbāna where all the cycles of defilement, actions, and results cease. Then no one in this Universe can find peace. In the absence of nibbāna, defilement will play havoc with our lives to produce action, which will bring about results, which will create conditions for the arising of a new group of aggregates attended by suffering. It is only the Path and its Fruition that can exterminate defilements, and this extermination will bring the cycle of suffering to an end. This cessation of suffering is real. Buddhas and Arahants actually reach this stage, and after their parinibbāna all sufferings come to an end.
No Primary Elements in Nibbāna
In nibbāna there are no element of earth or solidity, no element of water or fluidity, no element of fire or thermal energy, and no element of air or motive force that can usually be met with in the world of the senses, such as the world of men and devas, or in the world of Form, such as the world of corporeal brahmas, etc. Possessing solidity, men, devas, and brahmas assume shapes and forms. Cessation means the end of such shapes and forms that possess mass. In the absence of mass, there are no elements of fluidity, thermal energy, and motive force.
Matter is Non-existent in Nibbāna
In the absence of the four primary elements there can be no derived materiality (upāda rūpa) formed by these four elements, for instance, the eye and the sight, the ear and the sound, etc. Since they are absent there will be no phenomena of seeing, hearing, etc., which occur in the sensual realm as sense-sphere consciousness and in the Form Sphere as form-sphere consciousness.
Consider this: without eyes one cannot see, without ears one cannot hear, without nose one cannot smell, without tongue one cannot taste, and without body one cannot get the sensation of touch. The physical sense bases are the seat of sensation, or the five sense organs that form the bases of consciousness. Devoid of the organs of sense, consciousness cannot arise. In the world of the brahmas, only the eye-base (cakkhu pasāda) and ear-base (sota pasāda) exist — nose-base (ghāna pasāda), tongue-base (jivhā pasāda), and body-base (kāya pasāda) being absent. So brahmas may possess noses and tongues in rudimentary forms or bodies or masses in great dimensions, but they do not know what smell is, what taste is, or what bodily impression is. However, there is the seat of consciousness usually called the heart-base (hadaya vatthu), in all sentient beings, whether celestial or human. So in these three realms, thought, knowledge, and absorptions can occur.
As I have said, as there are no primary elements in nibbāna, all matter dependent on these four elements are non-existent. Because of the absence of matter, there is no consciousness appertaining to the realm of the senses or to the realm of form — as, for instance, the first jhānic consciousness. For brevity’s sake I will discuss only about mind (citta), but whenever mind is mentioned one must remember it is accompanied by mental concomitants (cetasikā). Now the question arises whether in nibbāna there are still extant consciousness that arises without depending on matter as, for example, formless consciousness.
Absence of Formless Consciousness
Here, the text is also very explicit about the absence of formless sphere consciousness in nibbāna, whether it be consciousness appertaining to the abode of the Infinity of Space, or to the abode of the Infinity of Consciousness, or to the abode of Nothingness, or to the abode of Neither Perception nor Non-perception. In the realm of the Infinity of Space, rebirth-linking begins with the advent of consciousness relating to kamma result, mind and mental concomitants. For ordinary people, during the course of existence between rebirth-linking and death, wholesome or unwholesome consciousness, together with their concomitants arise. When such ordinary people are duly trained in the Dhamma they are known as trainees (sekkha).
Such trainees may become Arahants when they are reborn in the realm of the infinity of Space. In that case, only wholesome and functional consciousness arise together with their respective concomitants, but matter is absent there. Only mind and mental concomitants — all in a state of flux — are present. In that realm all phenomena are psychical. It just occurs to me that psychic beings need no food, clothing, or shelter, but it is usual for artists to depict this realm and others of the Formless Sphere as having palaces and mansions. However, in nibbāna they will be superfluous, as in nibbāna there is neither mind or matter.
Today non-Buddhists have become highly interested in space, but the space they have in mind is space in the physical sense. They may not be able to assimilate the idea of the existence of the realm of Infinity of Space, but the Buddha clearly differentiates the realm of mind and its constituents together with its state of absorptions from the realm of no-mind where all its concomitants and absorptions are nullified. A meditator who concentrates his or her mind on the rise and fall of the aggregates can aspire to reach the stage of knowledge of equanimity about formations. If he or she reaches that stage, he or she would feel the disappearance of the physical self, experiencing only a stream of consciousness that floats in space. As his or her knowledge progresses, this stream will become clearer and clearer. Strictly speaking, this is not absorption on Infinity of Space, but it is an insight akin to that absorption.
From the foregoing it may also be adduced that there is no consciousness and its concomitant appertaining to the realm of Infinity of Consciousness, and the same may be said of consciousness and its concomitant appertaining to the realm of Nothingness, and of Neither Perception nor Non-perception. The highest plane of existence is where perception is so subtle that it can be described as an intermediate stage between perception and non-perception. Equally subtle are contact, feeling, consciousness, and mental formations — concomitants of the mind that can be met with in that realm. In nibbāna such subtleties of the mind are entirely absent.
Those lacking confidence in the Dhamma and unable to realise the attainment of jhāna or ecstatic meditation (samāpatti), dispute all teachings relating to the realms of existence just described. What such sceptics should do is to practise insight meditation as taught by the Buddha. If they do they will attain jhāna that belongs to the realm of Neither Perception nor Non-perception, and realise for themselves the difference between the jhānic state in the Formless Sphere and nibbāna where such a state becomes redundant. It is futile to reject jhāna and nibbāna without any practical investigation.
Absence of Mind and Matter in Nibbāna
In nibbāna there are no such things as mind or mental concomitants, which can be met with in the sense-sphere or form-sphere. It naturally follows that mind and matter that belong to the thirty-one planes of existence are totally absent in nibbāna. However, some would like to propose that after the parinibbāna of the Buddha and the Arahants, they acquire a special kind of mind and matter in nibbāna. Such an extraordinary way of thinking may appeal to those who cannot do away with self or ego.
With regard to this proposition a learned Sayādaw reasoned that if there is a special kind of mind and matter in nibbāna, there must also be a special kind of rebirth which gives rise to a special kind of old age, disease, and death, which in turn bring about a special kind of sorrow, lamentation, suffering, distress, and despair. When the teachings explicitly say cessation, it will be improper to go beyond it and formulate an idea of a special kind of existence. Extinction points to nothing other than Nothingness. Nibbāna, which is not involved in mind and matter, cannot be made to get involved either in this world or in other worlds.
Nibbāna is Beyond All Realms
Hence the text says, “nāyaṃ loko, na paraloko,” which means “neither in this world nor in other worlds.” In the absence of matter there can be no concept of darkness; and in the absence of the concept of darkness, there can be no concept of light. Hence in nibbāna there is no sun nor moon. Where no new bodies of the aggregates arise there can be no darkness or light. Yet the question might arise whether it is possible for sentient beings to come to nibbāna in the way that beings from the lower realms come to the human world, or beings from the human world come to the world of devas. However, in nibbāna there are no such comings. The usual term to describe the realisation of nibbāna is that the Buddhas and Arahants “enter” nibbāna, or specifically, anupādisesanibbāna. This does not mean the arrival of new aggregates, but the cutting off of the flow of mind and matter that causes existence. It is the complete extinction of aggregates; and this extinction is recognised as anupādisesanibbāna. It is not a place where beings make their landing from other planes of existence.
No one goes out or gets transported from nibbāna to other planes of existence either. Beings with wholesome kammas depart this human world for the world of devas; and those from heaven might also come down to earth as human beings. Those with unwholesome kammas might prefer going down to the lower realms. In nibbāna there is no such coming and going.
Venerable Mahasi Sayadaw. A selection from his work titled: On the Nature of Nibbana
I am posting this for informational purposes only. I am not reading or participating in this thread otherwise. So if anyone tries to talk to me in this thread and I don't answer, please know I'm not ignoring you, I'm just not participating in this thread at all beyond providing info