Duality of the world

The world as we have come to know it exists of two parts, which are linked and mirrored. The realm of physical and the realm of thoughts.
There are many ideas as to how to conceptualize this material/immaterial duality. Some scholars claim, that the physical realm is a shell around a core of thoughts, wherein the deepest core is the distilled essence of existence, thought that has sparked everything. Others claim it is the opposite, that the material is the core of the immaterial existence.
Around the world, the how and why differ, but everyone from the lowliest peasant to the mightiest king knows, that what they see with their eyes is not everything that exists.

The thoughts in the immaterial realm can take proper form, gain power and in turn affect the material plane. Thoughts are much easier to coalesce, they can become entities. Entire cities, if united can create powerful avatars in the immaterial realm. Unity is the power that brings about change. For good and bad.