The Flat People In 2-D World is the personification that is used as an example of the fact that we are not able to understand four dimensions quite yet. The Flat People in 2-D World are unaware of the concept of up. They are just things on paper, that only know length and width. It would undo their entire perception of reality if up were even to enter their imagination. In that way, we, as three-dimensional beings, cannot comprehend what four would be like. Is it possible? Everything is possible.