(POLITEIA from 515 A)
In his book Politeia, Plato uses a metaphor in order to make clear that what we perceive is a distortion, an idea of (higher) reality. This story, in summary, is as follows: A group of people have been confined in a cave since childhood and cannot move. The only reality these people know is therefore the play of shadows of themselves and of moving things on the wall opposite. The spatial manuscript works in a similar way. Reality can never be seen clearly from one half, the brain. The ‘perception sieve’ distorts reality. This always occurs in exactly the same way, so that interpretation is possible. As a result, it is possible to respond to this reality and to intervene, although uncertainty remains.