In the story "Allegory of the Cave" , in ancient times, there were three prisoners shackled in dark cave facing one direction day and night, taking place in ancient Greece.
The Introduction Of Shadows.
So that's where the shadows come from.
While living in the cave, shadows cast on a wall in front of the prisoners were their only reality because, they were shackled in this cave for all their lives. The prisoners observe these shadow cast on the wall by objects passing, but do not realize they are objects and unaware a fire is behind them.
Back Into the Darkness
Then, a prisoner was released free from the cave. The prisoner went outside the cave,and explored the outside world and was exposed to the sun.
A Different part Of Me
I can't see anything
The prisoner got to understand the shadows he saw inside the cave and began to realize it was all a reflection from the sun. The prisoner was very excited and very cheerful when he was released into the world.
When the prisoner was done exploring the outside world, he went back into the dark cave and it was still daylight; His eyesight became adjusted to the sun and was not use to the darkness. Also, since he was use to the sunlight and not the darkness he couldn't see the shadows anymore.
The prisoner reached to the end of the cave to tell his prisoner friends about the experience. The prisoner told his friends about his experience and responded to him as he was crazy. The two prisoners seen him struggling to see in the darkness, and was afraid by the sunlight he seen. The two prisoners now seen the other prisoner as a different person.