A Verb for Nirvana
Back in the days of the Buddha, nirvana (nibbana) had a verb of its own: nibbuti. It meant to "go out," like a flame. Because fire was thought to be in a state of entrapment as it burned — both clinging to and trapped by the fuel on which it fed — its going out was seen as an unbinding. To go out was to be unbound. Sometimes another verb was used — parinibbuti — with the "pari-" meaning total or all-around, to indicate that the person unbound, unlike fire unbound, would never again be trapped.
Now that nirvana has become an English word, it should have its own English verb to convey the sense of "being unbound" as well. At present, we say that a person "reaches" nirvana or "enters" nirvana, implying that nibbana is a place where you can go. But nirvana is most emphatically not a place. It's realized only when the mind stops defining itself in terms of place: of here, or there, or between the two.
This may seem like a word-chopper's problem — what can a verb or two do to your practice? — but the idea of nirvana as a place has created severe misunderstandings in the past, and it could easily create misunderstandings now. There was a time when some philosophers in India reasoned that if nirvana is one place and samsara another, then entering into nirvana leaves you stuck: you've limited your range of movement, for you can't get back to samsara. Thus to solve this problem they invented what they thought was a new kind of nirvana: an unestablished nirvana, in which one could be in both places — nirvana and samsara — at once.
However, these philosophers misunderstood two important points about the Buddha's teachings. The first was that neither samsara nor nirvana is a place. Samsara is a process of creating places, even whole worlds, (this is called becoming) and then wandering through them (this is called birth). Nirvana is the end of this process. You may be able to be in two places at once — or even develop a sense of self so infinite that you can occupy all places at once — but you can't feed a process and experience its end at the same time. You're either feeding samsara or you're not. If you feel the need to course freely through both samsara and nirvana, you're simply engaging in more samsara-ing and keeping yourself trapped.
The second point is that nirvana, from the very beginning, was realized through unestablished consciousness — one that doesn't come or go or stay in place. There's no way that anything unestablished can get stuck anywhere at all, for it's not only non-localized but also undefined.
The idea of a religious ideal as lying beyond space and definition is not exclusive to the Buddha's teachings, but issues of locality and definition, in the Buddha's eyes, had a specific psychological meaning. This is why the non-locality of nirvana is important to understand.
Just as all phenomena are rooted in desire, consciousness localizes itself through passion. Passion is what creates the "there" on which consciousness can land or get established, whether the "there" is a form, feeling, perception, thought-construct, or a type of consciousness itself. Once consciousness gets established on any of these aggregates, it becomes attached and then proliferates, feeding on everything around it and creating all sorts of havoc. Wherever there's attachment, that's where you get defined as a being. You create an identity there, and in so doing you're limited there. Even if the "there" is an infinite sense of awareness grounding, surrounding, or permeating everything else, it's still limited, for "grounding" and so forth are aspects of place. Wherever there's place, no matter how subtle, passion lies latent, looking for more food to feed on.
If, however, the passion can be removed, there's no more "there" there. One sutta illustrates this with a simile: the sun shining through the eastern wall of a house and landing on the western wall. If the western wall, the ground beneath it, and the waters beneath the ground were all removed, the sunlight wouldn't land. In the same way, if passion for form, etc., could be removed, consciousness would have no "where" to land, and so would become unestablished. This doesn't mean that consciousness would be annihilated, simply that — like the sunlight — it would now have no locality. With no locality, it would no longer be defined.
This is why the consciousness of nirvana is said to be "without surface" (anidassanam), for it doesn't land. Because the consciousness-aggregate covers only consciousness that is near or far, past, present, or future — i.e., in connection with space and time — consciousness without surface is not included in the aggregates. It's not eternal because eternity is a function of time. And because non-local also means undefined, the Buddha insisted that an awakened person — unlike ordinary people — can't be located or defined in any relation to the aggregates in this life; after death, he/she can't be described as existing, not existing, neither, or both, because descriptions can apply only to definable things.
The essential step toward this non-localized, undefined realization is to cut back on the proliferations of consciousness. This first involves contemplating the drawbacks of keeping consciousness trapped in the process of feeding. This contemplation gives urgency to the next steps: bringing the mind to oneness in concentration, gradually refining that oneness, and then dropping it to zero. The drawbacks of feeding are most graphically described in SN 12.63, A Son's Flesh. The process of gradually refining oneness is probably best described in MN 121, The Lesser Discourse on Emptiness, while the drop to zero is best described in the Buddha's famous instructions to Bahiya: "'In reference to the seen, there will be only the seen. In reference to the heard, only the heard. In reference to the sensed, only the sensed. In reference to the cognized, only the cognized.' That is how you should train yourself. When for you there will be only the seen in reference to the seen, only the heard in reference to the heard, only the sensed in reference to the sensed, only the cognized in reference to the cognized, then, Bahiya, there is no you in connection with that. When there is no you in connection with that, there is no you there. When there is no you there, you are neither here nor yonder nor between the two. This, just this, is the end of stress."
With no here or there or between the two, you obviously can't use the verb "enter" or "reach" to describe this realization, even metaphorically. Maybe we should make the word nirvana into a verb itself: "When there is no you in connection with that, you nirvana." That way we can indicate that unbinding is an action unlike any other, and we can head off any mistaken notion about getting "stuck" in total freedom.