The world exists in a multi-tiered structure, and this is often considered a universal norm. In the vast majority of mythologies, the world is divided into two distinct realms: one that symbolizes the bright aspect and another that symbolizes the dark aspect.
Even with the continuation of myth, this subdivision of the world can further evolve. Just like the thirty-three heavens of the East and the heaven and hell of the West seem to reflect an issue: as human society becomes more complex with development, so too presumably should the world. A multi-layered structure facilitates its internal growth and the stability of the world itself.
