As the Zen poet Ryokan said:
"If someone asks what is the mark of enlightenment or illusion,
I cannot say -- wealth and honor are nothing but dust,
As the evening rain falls, I sit in my hermitage
And stretch out both feet in answer."
Enlightenment is often put up on a pedestal of perfection, and perhaps only a few out of billions have gone far enough to be substantially beyond severe physical suffering. At such an extreme of non-attachment and non-identification, the pain simply arises and passes as it is, without resistance or stress. But it's not necessarily all "good" at that point. It becomes somewhat pathological, at least from the standpoint of society. Ramana Maharshi was said to have let rats eat the flesh of his legs. We might question whether this was truly the best use of the amazing insight of Ramana.
In the article "Drowning Mr. M" (SciAm Mind April 2005), we find a person suffering from athymhormia, a profound lack of attachment and motivation, due to lesions on the brain. Taking a dip in the pool, he finds himself underwater and simply begins to let himself drown. He doesn't care. It doesn't bother him. The sight of his daughter, though, breaks the apathy and he returns to the surface. For these people, "it is as if they have become mere spectators to their own lives, no longer actively participating."
In many ways (credit to Shinzen Young) this condition mimics a high degree of enlightenment. The interesting thing about athymhormia is that unlike other related experiences, there is no depression or cognitive impairment, the person is just very unattached. They feel pain but it doesn't affect them.
And there are accounts of many such as Katie Byron, where it took her a long time to adjust to her extreme version of enlightenment. For example, she couldn't understand why strangers on the street didn't know her, because from her perspective they were the same person.
The standard definition for enlightenment would be something like the falling away of the ego. But this is not necessarily easy to fathom unless one has actually experienced it.
In some ways enlightenment represents the falling away of false beliefs about the self, the loss of a certain kind of neuroticism.
From Karen Horney, (Neurosis and Human Growth: The Struggle Towards Self-Realization):
The infinite powers the neurotic ascribes to himself are, after all, powers of the mind. No wonder, then, that he is fascinated by it and proud of it. The idealized image is a product of his imagination. But this is not something created overnight. Incessant work of intellect and imagination, most of it unconscious, goes into maintaining the private fictitious world through rationalizations, justifications, externalizations, reconciling irreconcilables - in short, through finding ways to make things appear different than what they are. The more a person is alienated from himself, the more his mind becomes supreme reality.
Only when the patient has become interested in the question "Who am I?" will the analyst more actively try to bring to his awareness how little he does know or care about his real feelings, wishes, or beliefs.
The patient may simply feel sympathetic toward himself and experience himself for the first time as being neither particularly wonderful nor despicable but as the struggling and often harassed human being which he really is.
Moreover any move toward being himself gives him a sense of fulfillment which is different from anything he has known before. And while such experience is at first short lived, it may in time recur more and more often and for periods of longer duration.
From the standpoint of individuals, it is important to notice that we weren't always ego-based creatures. There was a bit of time, however brief, as say a fetus and a newborn, when we really didn't know we were anything.
Didn't know we were separate, or male or female, good or bad, rich or poor, or human, or anything. Didn't have politics or religion, or categories period. Didn't have gender, ethnicity, social class, occupation, hobbies, culture. Didn't have parents, friends, or family, at least in the sense that we didn't know what those things were. Didn't have status, self-esteem, reputation, body image, commitments, achievements, losses, gains. Didn't have characteristics, values, beliefs, attitudes, ideas, habits.
Didn't have identity or uniqueness. Didn't know we were separate. Didn't have past or future, time or space, or age or continuity. Everything was just happening, and there were no decisions that we could call conscious.
So what is that like?
What we're pointing at is pure, nonconceptual awareness, prior, in a sense, to the arising of anything. All of those things listed above are attachment points for identity. With those things dialed down, there is a lot of freedom to simply be who we are, instead of what we or other people think.
So pure consciousness or awareness or suchness, without ideas or conception, is a pointer.
Alfred Lord Tennyson used a type of meditation to pierce the veil:
"... when I have been all alone. This has often come upon me through repeating my own name to myself silently till, all at once, as it were, out of the intensity of the consciousness of individuality, the individuality itself seemed to dissolve and fade away into boundless being; and this not a confused state, but the clearest of the clearest, the surest of the surest, the weirdest of the weirdest, utterly beyond words, where death was an almost laughable impossibility, the loss of personality (if so it were) seeming no extinction, but the only true life"
Anyone can have a moment of that, but generally people's assumptions and attachments are so strong they go right back to their assumed identity. A person could get a powerful sense of this during a psychedelic experience, and in some way it might lightly affect them, but mostly people will go back to their old ways.
So something could be said about both a degree of liberation, which could be massive in a temporary experience of just one moment, and also the degree to which that liberation is permanent. Someone who is enlightened would have a substantial degree of both.
From another angle, we might look to science, which points out that we don't ever have any direct contact with what we call the universe. Our senses feed into a brain, which creates a map, and that map is all we ever experience. As you perceive it, the universe IS your consciousness, always has been. Everything you have ever experienced is you, is consciousness, and that is all we can know in an absolute way. Some may find that hard to swallow, but it is an important pointer.
This is basically the insight of Plato's analogy of the cave. All we can see are shadows on the wall of the cave, yet we cannot actually see what is casting the shadows.
And again from a scientific view, we can't really consider ourselves to be quite so separate as we might ordinarily conceive. Not only do we live in a massively interconnected human world, each ultimately dependent on everyone else, and all of our beliefs formed by our interactions with others, but at a fundamental level we do not exist without oxygen or food or water, which means we do not exist without plants, or the earth, or the entire universe. We are not separate from the totality.
We can generally understand that an amoeba has no self. It is just a little organic machine, doing what it does, genetics plus environment. As we go up to multi-cellular creatures, perhaps we can still see that something like an earthworm or a grasshopper has no self. Just little organic machines, doing what they do. For a lot of people this exercise gets more difficult as we get up to the mammals. But it's the same thing. A mouse or a goat is just an organic machine that does what it does. By the time we get to dogs and cats, many people will begin to disagree. But it's the same thing. You take those genetics, you put them in that environment, that's what you get, organic machines doing what they do.
So yeah, the kind of dry and unappealing spin is that we are soulless robots. But waking up to that and beginning to see how your mental machinery was indoctrinated, and letting go of that unskillful programming, that's a beautiful thing. Once again though, it's also just your particular genetics doing what they are doing in your particular environment.
The enlightened viewpoint might seem "wrong" in a way from the assumptions of consensus civilization. ("Oh, but of course I have a self"). But in many ways it is the enlightened mind that is actually letting go of what isn't real, the phantoms of belief, opinion, and assumption.
And that intellectual path of seeing what we are conceptually is one thing, but circling back, the really important thing is to experience and see from the viewpoint of pure consciousness.
The enlightened mind is a mind relatively absent of assumptions or elaborations, one that is not taking the bait of craving or resistance. Less compressed, more relaxed, less closed, more open, less reactive, more responsive, less self-obsessed, more compassionate, less compulsive, more free.
There is a kind of relaxation that takes place when all of this striving is let go of. The mind has been conditioned to "flex" and strive, in a way. Continually practicing to be aware of that flexing and to let go of it, this is the path. Eventually the mind begins to relax in this way. The letting go of the grasping of self-identity is one aspect of this relaxation. With enough practice, the mind breaks free of prior assumptions and begins to adopt relaxed awareness as its new default. It begins to "identify" with the background of experience, with pure consciousness. As this becomes permanent, this absence of assumptions, seeing what actually is, this is what we call enlightenment.
All visible objects are but as pasteboard masks. If man will strike, strike through the mask!
-Ahab, from Moby Dick