The Allegory of the Cave
SOCRATES: Imagine this: People live under the earth in a cavelike dwelling. Stretching a long way up toward the daylight is its entrance, toward which the entire cave is gathered. The people have been in this dwelling since childhood, shackled by the legs and neck. Thus they stay in the same place so that there is only one thing for them to look that: whatever they encounter in front of their faces. But because they are shackled, they are unable to turn their heads around.
Some light, of course, is allowed them, namely from a fire that casts its glow toward them from behind them, being above and at some distance. Between the fire and those who are shackled [i.e., behind their backs] there runs a walkway at a certain height. Imagine that a low wall has been built the length of the walkway, like the low curtain that puppeteers put up, over which they show their puppets.
So now imagine that all along this low wall people are carrying all sorts of things that reach up higher than the wall: statues and other carvings made of stone or wood and many other artifacts that people have made. As you would expect, some are talking to each other [as they walk along] and some are silent.
GLAUCON: This is an unusual picture that you are presenting here, and these are unusual prisoners.
SOCRATES: They are very much like us humans, I [Socrates] responded.
SOCRATES: What do you think? From the beginning people like this have never managed, whether on their own or with the help by others, to see anything besides the shadows that are [continually] projected on the wall opposite them by the glow of the fire.
GLAUCON: How could it be otherwise, since they are forced to keep their heads immobile for their entire lives?
SOCRATES: And what do they see of the things that are being carried along [behind them]? Do they not see simply these [namely the shadows]?
SOCRATES: Now if they were able to say something about what they saw and to talk it over, do you not think that they would regard that which they saw on the wall as beings? GLAUCON: They would have to.
SOCRATES: And now what if this prison also had an echo reverberating off the wall in front of them [the one that they always and only look at]? Whenever one of the people walking behind those in chains (and carrying the things) would make a sound, do you think the prisoners would imagine that the speaker were anyone other than the shadow passing in front of them?
GLAUCON: Nothing else, by Zeus!
SOCRATES: All in all, I responded, those who were chained would consider nothing besides the shadows of the artifacts as the unhidden.
GLAUCON: That would absolutely have to be.
SOCRATES: So now, I replied, watch the process whereby the prisoners are set free from their chains and, along with that, cured of their lack of insight, and likewise consider what kind of lack of insight must be if the following were to happen to those who were chained.
Whenever any of them was unchained and was forced to stand up suddenly, to turn around, to walk, and to look up toward the light, in each case the person would be able to do this only with pain and because of the flickering brightness would be unable to look at those things whose shadows he previously saw.
If all this were to happen to the prisoner, what do you think he would say if someone were to inform him that what he saw before were [mere] trifles but that now he was much nearer to beings; and that, as a consequence of now being turned toward what is more in being, he also saw more correctly?
And if someone were [then] to show him any of the things that were passing by and forced him to answer the question about what it was, don't you think that he would be a wit's end and in addition would consider that what he previously saw [with is own eyes] was more unhidden than what was now being shown [to him by someone else].
GLAUCON: Yes, absolutely.
SOCRATES: And if someone even forced him to look into the glare of the fire, would his eyes not hurt him, and would he not then turn away and flee [back] to that which he is capable of looking at? And would he not decide that [what he could see before without any help] was in fact clearer than what was now being shown to him?
SOCRATES: Now, however, if someone, using force, were to pull him [who had been freed from his chains] away from there and to drag him up the cave's rough and steep ascent and not to let go of him until he had dragged him out into the light of the sun would not the one who had been dragged like this feel, in the process, pain and rage? And when he got into the sunlight, wouldn't his eyes be filled with the glare, and wouldn't he thus be unable to see any of the things that are now revealed to him as the unhidden?
GLAUCON: He would not be able to do that at all, at least not right away.
SOCRATES: It would obviously take some getting accustomed, I think, if it should be a matter of taking into one's eyes that which is up there outside the cave, in the light of the sun.
SOCRATES: And in this process of acclimatization he would first and most easily be able to look at shadows and after that the images of people and the rest of things as they are reflected in water.
Later, however, he would be able to view the things themselves [the beings, instead of the dim reflections]. But within the range of such things, he might well contemplate what there is in the heavenly dome, and this dome itself, more easily during the night by looking at the light of the stars and the moon, [more easily, that is to say,] than by looking at the sun and its glare during the day.
SOCRATES: But I think that finally he would be in the condition to look at the sun itself, not just at its reflection whether in water or wherever else it might appear, but at the sun itself, as it is in and of itself and in the place proper to it and to contemplate of what sort it is.
GLAUCON: It would necessarily happen this way.
SOCRATES: And having done all that, by this time he would also be able to gather the following about the sun: that it is that which grants both the seasons and the years; it is that which governs whatever there is in the now visible region of sunlight; and that it is also the cause of all those things that the people dwelling in the cave have before they eyes in some way or other.
GLAUCON: It is obvious that he would get to these things -- the sun and whatever stands in its light -- after he had gone out beyond those previous things, the merely reflections and shadows.
SOCRATES: And then what? If he again recalled his first dwelling, and the "knowing" that passes as the norm there, and the people with whom he once was chained, don't you think he would consider himself lucky because of the transformation that had happened and, by contrast, feel sorry for them?
GLAUCON: Very much so.
SOCRATES: However, what if among the people in the previous dwelling place, the cave, certain honors and commendations were established for whomever most clearly catches sight of what passes by and also best remembers which of them normally is brought by first, which one later, and which ones at the same time? And what if there were honors for whoever could most easily foresee which one might come by next?
Do you think the one who had gotten out of the cave would still envy those within the cave and would want to compete with them who are esteemed and who have power? Or would not he or she much rather wish for the condition that Homer speaks of, namely "to live on the land [above ground] as the paid menial of another destitute peasant"? Wouldn't he or she prefer to put up with absolutely anything else rather than associate with those opinions that hold in the cave and be that kind of human being?
GLAUCON: I think that he would prefer to endure everything rather than be that kind of human being.
SOCRATES: And now, I responded, consider this: If this person who had gotten out of the cave were to go back down again and sit in the same place as before, would he not find in that case, coming suddenly out of the sunlight, that his eyes are filled with darkness?"
GLAUCON: Yes, very much so.
SOCRATES: Now if once again, along with those who had remained shackled there, the freed person had to engage in the business of asserting and maintaining opinions about the shadows -- while his eyes are still weak and before they have readjusted, an adjustment that would require quite a bit of time -- would he not then be exposed to ridicule down there? And would they not let him know that he had gone up but only in order to come back down into the cave with his eyes ruined -- and thus it certainly does not pay to go up.
And if they can get hold of this person who takes it in hand to free them from their chains and to lead them up, and if they could kill him, will they not actually kill him?
GLAUCON: They certainly will.
Plato, Republic, VII (514 a, 2 to 517 a, 7)
Translation by Thomas Sheehan