The Allegory of the Cave is an allegory used by the Greek philosopher Plato in his work The Republic (Politeia) to illustrate "our nature in its education and want of education". The allegory is written as a fictional dialogue between Plato's teacher Socrates and Plato's brother Glaucon, at the beginning of Book VII (514a–520a).

Plato imagines a group of people who have lived chained in a cave all of their lives, facing a blank wall. The people watch shadows projected on the wall by things passing in front of a fire behind them, and begin to ascribe forms to these shadows. According to Plato, the shadows are as close as the prisoners get to seeing reality. He then explains how the philosopher is like a prisoner who is freed from the cave and comes to understand that the shadows on the wall are not constitutive of reality at all, as he can perceive the true form of reality rather than the mere shadows seen by the prisoners.

The Allegory is related to Plato's Theory of Forms, wherein Plato asserts that "Forms" (or "Ideas"), and not the material world of change known to us through sensation, possess the highest and most fundamental kind of reality. Only knowledge of the Forms constitutes real knowledge. In addition, the allegory of the cave is an attempt to explain the philosopher's place in society.

It touches also Plato's metaphor of the sun and the analogy of the divided line, which immediately precede it at the end of Book VI. Allegories are summarized in the viewpoint of dialectic at the end of Book VII and VIII (531d-534e). This relates to the idea of forms as people struggle to see the reality beyond illusion. Plato stresses the importance of goodness and goes on to offer allegories. The allegory of the cave is the longest and most famous of three allegories.

It requires knowledge of goodness to manage a community well.
Those who gain such knowledge have to 'return to the cave':
paradoxically, those who least want power are the ones who should have it.

'Next', I said, 'here's a situation which you can use as an analogy for the human condition - for our education or lack of it. Imagine people living in a cavernous cell down under the ground; at far end of the cave, a long way off, there's an entrance open to the outside world. They've been there since childhood, with their legs and necks tied up in a way which keeps them in one place and allows them to look only straight ahead, but not to turn their heads. There's firelight burning a long way further up the cave behind them, and up the slope between the fire and the prisoners there's a road, beside which you should imagine a low wall has been built - like the partition which conjurors place between themselves and their audience and above which they show their tricks.'
'All right,' he said.
'Imagine also that there are people on other side of this wall who are carrying all sorts of artefacts. These artefacts, human statuettes, and animals models carved in stone and wood and all kinds of material stick out over the wall; and as you'd expect, some of the people talk as they carry these objects along, while others are silent.'
'This is a strange picture you're painting', he said, 'with strange prisoners.'
'They're no different from us,' I said. 'I mean, in the first place, do you think they'd see anything of themselves and one another except the shadow cast by the fire on to the cave wall directly opposite them?'
'Of course not,' he said. 'They're forced to spend their lives without moving their heads.'
'And what about the objects which were being carried along? Won't they only see their shadows as well?'
'Now, suppose they were able to talk to one another: don't you think they 'd assume that their words applied to what they saw passing by in front of them?'
'They couldn't think otherwise.'
'And what if sound echoed off the prison wall opposite them? When any of the passers-by spoke, don't you think they'd be bound to assume that the sound came from a passing shadow?'
'I'm absolutely certain of it,' he said.
'All in all, then,' I said, 'the shadows of artefacts would constitute the only reality people in this situation would recognize.'
'That's absolutely inevitable,' he agreed.
'What do you think would happen, then,' I asked, 'if they were set free from their bonds and cured of their inanity? What would it be like if they found that happening to them? Imagine that one of them has been set free and is suddenly made to stand up, to turn his head and walk, and to look towards the firelight. It hurts him to do all this and he's too dazzled to be capable of making out the objects whose shadows he'd formerly been looking at. And suppose someone tells him that what he's been seeing all this time has no substance, and that he's now closer to reality and is seeing more accurately, because of the greater reality of the things in front of his eyes - what do you imagine his reaction would be? And what do you think he'd say if he were shown any of the passing objects and had to respond to being asked what it was? Don't you think he'd be bewildered and would think that there was more reality in what he'd been seeing before than in what he was being shown now?'
'Far more,' he said.
'And if he were forced to look at the actual firelight, don't you think it would hurt his eyes? Don't you think he'd turn away and run back to the things he could make out, and would take the truth of the matter to be that these things are clearer than what he was being shown?'
'Yes,' he agreed.
'And imagine him being dragged forcibly away from there up the rough, steep slope,' I went on, 'without being released until he's been pulled out into the sunlight. Wouldn't this treatment cause him pain and distress? And once he's reached the sunlight, he wouldn't be able to see a single one of the things which are currently taken to be real, would he, because his eyes would be overwhelmed by the sun's beams?'
'No, he wouldn't,' he answered, 'not straight away.'
'He wouldn't be able to see things up on the surface of the earth, I suppose, until he'd got used to his situation. At first, it would be shadows that he could most easily make out, then he'd move on to the reflections of people and so on in water, and later he'd be able to see the actual things themselves. Next, he'd feast his eyes on the heavenly bodies and the heavens themselves, which would be easier at night: he'd look at the light of the starts and the moon, rather than at the sun and sunlight during the daytime.'
'Of course.'
'And at last, I imagine, he'd be able to discern and feast his eyes on the sun - not the displaced image of the sun in water or elsewhere, but the sun on its own, in its proper place.'
'Yes, he'd inevitably come to that,' he said.
'After that, he'd start to think about the sun and he'd decude that it is the source of the seasons and the yearly cycle, that the whole of the visible realm is its domain, and that in a sense everything which he and his peers used to see is its responsibility.'
'Yes, that would obviously be the next point he'd come to,' he agreed.
'Now, if he recalled the cell where he'd originally lived and what passed for knowledge there and his former fellow prisoners, don't you think he'd feel happy about his own altered circumstances, and sorry for them?'

'Suppose that the prisoners used to assign prestige and credit to one another, in the sense that they rewarded speed at recognizing the shadows as they passed, and the ability to remember which ones normally come earlier and later and at the same time as which other ones, and expertise at using this as a basis for guessing which ones would arrive next.
Do you think our former prisoner would covet these honours and would envy the people who had status and power there, or would he much prefer, as Homer describes it, "being a slave labouring for someone else - someone without property", and would put up with anything at all, in fact, rather share their beliefs and their life?'
'Yes, I think he'd go through anything rather than live that way,' he said.
'Here's something else I'd like your opinion about,' I said. 'If he went back underground and sat down again in the same spot, wouldn't the sudden transition from the sunlight mean that his eyes would be overwhelmed by darkness?'
'Certainly,' he replied.
'Now, the process of adjustment would be quite long this time, and suppose that before his eyes had settled down and while he wasn't seeing well, he had once again to compete against those same old prisoners at identifying those shadows. Wouldn't he make a fool of himself? Wouldn't they say that he'd come back from his upward journey with eyes ruined, and that it wasn't even worth trying to go up there? And wouldn't they - if they could - grab hold of anyone who tried to set them free and take them up there, and kill him?'
'They certainly would,' he said.
'Well, my dear Glaucon,' I said, 'you should apply this allegory, as a whole, to what we were talking about before. The region which is accessible to sight should be equated with the prison cell, and the firelight there with the light of the sun. And if you think of the upward journey and the sight of things up on the surface of the earth as the mind's ascent to the intelligible realm, you won't be wrong - at least, I don't think you'd be wrong, and it's my impression that you want to hear. Only God knows if it's avtually true, however. Anyway, it's my opinion that the last thing to be seen - and it isn't easy to see either - in the realm of knowledge is goodness; and the sight of the character of goodness leads one to deduce that it is responsible for everything that is right and fine, whatever the circumstances, and that in the visible realm it is the progenitor of light and of the source of light, and in the intelligible realm it is the source and provider of truth and knowledge. And I also think that the sight of it is a prerequisite for intelligent conduct either of one's own private affairs or of public business.'
'I couldn't agree more,' he said.
'All right, then,' I said. 'I wonder if you also agree with me in not finding it strange that people who've travelled there don't want to engage in human business: there's nowhere else their minds would ever rather be than in the upper region - which is hardly surprising, if our allegory has got this aspect right as well.'
'No, it's not surprising,' he agreed.
Well, what about this?' I asked. 'Imagine someone returnin to the human world and all its misery after contemplating the divine realm. Do you think it's surprising if he seems awkward and ridiculous while he's still not seeing well, before he's had time to adjust to the darkness of his situation, and into a competition whose terms are the conceptions of morality held by people who have never seen morality itself?'
'No, that's not surprising in the slightest,' he said.
'In fact anyone with any sense,' I said, 'would remember that the eyes can become confused in two different ways, as a result of two different sets of circumstances: it can happen in the transition from light to darkness, and also in the transition from darkness to light. If he took the same facts into consideration when he also noticed someone's mind in such a state of confusion that it was incapable of making anything out, his reaction wouldn't be unthinking ridicule. Instead, he'd try to find out whether this person's mind was returning from a mode of existence which involves greater lucidity and had been blinded by the unfamiliar darkness, or whether it was moving from relative ignorance to relative lucidity and had been overwhelmed and dazzled by the increasd brightness. Once he'd distinguished between the two conditions and modes of existence, he'd congratulate anyone he found in the second state, and feel sorry for anyone in the first state. If he did choose to laugh at someone in the second state, his amusement would be less absurd than when laughter is directed at someone returning from the light above.'
'Yes,' he said, 'you're making a lot of sense.'

It requires knowledge of goodness to manage a community well. Those who gain such knowledge have to 'return to the cave': paradoxically, those who least want power are the ones who should have it.

'Now, if this is true,' I said, 'we must bear in mind that education is not capable of doing what some people promise. They claim to introduce knowledge into a mind which doesn't have it, as if they were introducing sight into eyes which are blind.'
'Yes, they do,' he said.
'An implication of what we're saying at the moment, however,' I pointed out, 'is that the capacity for knowledge is present in everyone's mind. If you can imagine an eye that can turn from darkness to brightness only if the body as a whole turns, then our organ of understanding is like that. Its orientation has to be accompanied by turning the mind as a whole away from the world of becoming, until it becomes capable of bearing the sight of real being and reality at its most bright, which we're saying is goodness. Yes?'
'That's what education should be,' I said, 'the art of orientation. Educators should devise the simplest and most effective methods of turning minds around. It shouldn't be the art of implanting sight in the organ, but should proceed on the understanding that the organ already has the capacity, but is improperly aligned and isn't facing the right way.'
'I suppose you're right,' he said.
'So, although the mental states which are described as good generally seem to resemble good physical states, in the sense that habituation and training do in fact implant them where they used not to be, yet understanding (as it turns out) is undoubtedly a property of something which is more divine: it never loses its power, and it is useful and beneficial, or useless and harmful, depending on its orientation.

For example, surely you've noticed how the petty minds of those who are acknowledged to be bad, but clever, are sharp-eyed and perceptive enough to gain insights into matters they direct their attention towards. It's not as if they weren't sharp-sighted, but their minds are forced to serve evil, and consequently the keener their vision is, the greater the evil they accomplish.'
'Yes, I've noticed this,' he said.
'However', I went on, 'if this aspect of that kind of person is hammered at from an early age, until the inevitable consequences of incarnation have been knocked off it - the leaden weights, so to speak, which are grafted on to it as a result of eating and similar pleasures and indulgences and which turn the sight of the mind downwards - if it sheds these weights and is oriented towards the truth, then (and we're talking about the same organ and the same people) it would see the truth just as clearly as it sees the objects it faces at the moment.'
'Yes, that make sense,' he said.
'Well, doesn't this make sense as well?' I asked. 'Or rather, isn't it an inevitable consequence of what we've been saying that uneducated people, who have no experience of truth, would make incompetent administrators of a community, and that the same goes for people who are allowed to spend their whole lives educating themselves? The first group would be no good because their lives lack direction; they've got no single point of reference to guide them in all their affairs, whether private or public. The second group would be no good because their hearts wouldn't be in the business: they think they've been transported to the Isles of the Blessed even while they're still alive.'
'True,' he said.
'Our job as founders, then,' I said, 'is to make sure that the best people come to that fundamental field of study (as we called it earlier): we must have them make the ascent we've been talking about and see goodness.

And afterwards, once they've been up there and had a good look, we mustn't let them get away with what they do at the moment.
'Which is what?'
'Staying there,' I replied, 'and refusing to come back down again to those prisoners, to share their work and their rewards, no matter whether those rewards are trivial or significant.'
'But in that case,' he protested, 'we'll be wronging them: we'll be making the quality of their lives worse and denying them the better life they could be living, won't we?'
'You're again forgetting, my friend,' I said, 'that the point of legislation is not to make one section of a community better of than the rest, but to engineer this for the community as a whole. Legislators should persuade or compel the members of a community to mesh together, should make every individual share with his fellows the benefit which he is capable of contributing to the common welfare, and should ensure that the community does contain people with this capacity; and the purpose of all this is not for legislators to leave people to choose their own direction, but for them to use people to bind the community together,'
'Yes, you're right,' he said. 'I was forgetting.'
'I think you'll also find, Glaucon,' I said, 'that we won't be wronging any philosophers who arise in our community. Our remarks, as we force them to take care of their fellow citizens and be their guardians, will be perfectly fair. We'll tell them that it's reasonable for philosophers who happen to occur in other communities not to share the work of those communities, since their occurrence was spontaneous, rather than planned by the political system of any of the communities in question, and it's fair for anything which arises spontaneously and doesn't owe its nurture to anyone or anything to have no interest in repaying anyone for having provided its nourishment. "Whe've bred you, however," we'll say, "to act, as it were, as the hive's leaders and kings, for your own good as well as that of the rest of the community. You've received a better and more thorough education than those other philosophers, and you're more capable of playing a part in both spheres. So each of you must, when your time comes, descend to where the rest of the community lives, and get used to looking at things in the dark. The point is that once you become acclimatized, you'll see infintely better than the others there; your experience of genuine right, morality, and goodness will enable you to identify every one of the images and recognize what it is an image of. And then the administration of our community - ours as well as yours - will be in the hands of people who are awake, as a distinct from the norm nowadays of communities being governed by people who shadow-box and fall out with one another in their dreams over who should rule, as if that were a highly desirable thing to do. No, the truth of the matter is this: the less keen the would-be rulers of a community are to rule, the better and less divided the administration of that community is bound to be, but where the rulers feel the opposite, the administration is bound to be the opposite.'
'Yes,' he said.
'And do you think our wards will greet these views of ours with scepticism and will refuse to join in the work of government when their time comes, when they can still spend most of their time living with one another in the untainted realm?
'No, they couldn't,' he answered. 'They're fair-minded people, and the instructions we're giving them are fair. However, they'll undoubtedly approach rulership as an inescapable duty - an attitude which is the opposite of the one held by the people who have power in communities at the moment.'
'You're right, Glaucon,' I said. 'You'll only have a well-governed community if you can come up with a way of life for your prospective rulers that is preferable to ruling! The point is that this is the only kind of community where the rulers will be genuinely well of (not in material terms, but they'll possess the wealth which is a prerequisite of happiness - a life of virtue and intelligence), whereas if government falls into the hands of people who are impoverished and starved of any good things of their own, and who expect to wrest some good for themselves from political office, a well-governed community is an impossibility. I mean, when rulership becomes smething to fight for, a domestic and internal war like this destroyes not only the perpetrators, but also the rest of the community.'
'You're absolutely right,' he said.
'Apart from the philosophical life,' I said, 'is there any way of life, in your opinion, which looks down on political office?'
'No, definitely not,' he answered.
'In fact, political power should be in the hands of people who aren't enamoured of it. Otherwise their rivals in love will fight them for it.'
'Of course.'
'There is no one you'd rather force to undertake the guarding of your community, then, than those who are experts in the factors which contribute towards the good government of a community, who don't look to politics for their rewards, and whose life is better than the political life. Agreed?'
'Yes,' he said.