„To show this diagram properly, I would really need a four dimensional screen. However, because of government cuts, we could manage to provide only a two dimensional screen.“

— Stephen Hawking
„If a shadow is a two-dimensional projection of the three-dimensional world, then the three-dimensional world as we know it is the projection of the four-dimensional Universe.“
— Marcel Duchamp
„This hero and villain no more understand Krazy Kat than the mythical denizens of a two dimensional realm understand some three dimensional intruder.“
— E.E. Cummings