Imagine a cave.
Inside there are people chained in place, unable to move even the slightest. The people have been chained in those positions, facing a wall in front of them, since the beginning of their existence.
Out of sight behind them, there is a fire.
There are various things moving between the prisoners and the fire, casting shadows on the wall that the prisoners are forced to watch.
Since the prisoners know nothing other than the shadows on the wall, they believe the shadows to be existence.
They name the shadows just as people named objects in the ‘real’ world.
The prisoners spend their existence watching the shadows on the wall, believing it to be all there is to their lives.
Imagine that one of the prisoners is freed from their chains.
The person turns around and views the rest of the cave for the first time.
They realize that what they ‘knew’ to be the world (shadows on the wall) is not all there is to existence.
The person sees the flame, the objects, and even the other people in the cave.
The other people explain that what the prisoner thought was the world were only shadows on a wall, meaningless.
The freed person examines the cave until eventually they leave the cave.
The light from the Sun hurts their eyes.
Once their eyes adjust, they see the outside.
They see plants, water, the sky, the sun.
They feel the warmth of the light, the coolness of the water, the change of the wind.
The person returns to the cave to explain the things that they’ve learned since becoming free.
The other prisoners likely resist this new information.
They refuse to accept anything other than the shadows on the wall
If they were free, they might even attempt to kill the person in order to maintain the status quo of the wall.