A cosmology is necessary to navigate the spirit realm. It is your personal map that provides contextual understanding for what you experience within it. A cosmological understanding also helps focus one’s intention in what one is truly trying to accomplish.
The composition of a cosmology should contain an explanation of the landscape of the spirit realm, and how it functions, as well as how the physical world and the spirit world relate to each other.
My cosmology assumes that the definition of spirit is equal to that of pure potentiality. This world is an “ideal”, but not in the sense that everything is good and perfect. It is abstract in the sense that it is not physical, and taken together it contains all aspects of all instances.
The spirit world is not bound by time. In spirit, everything that is possible exists simultaneously.
One of my spirit helpers has told me that the spirit world can be thought of as a coil. What extends the spirit world from being one infinitely-packed point is the idea of time. Shamanic societies usually break the spirit world up into three realms: the upper, middle, and lower worlds. However, the explanations of these realms are fairly vague across the board. In my cosmology, the real distinction between the realms is time. Future, Present, and Past represent the upper, middle, and lower realms respectively. In my studies I have not encountered this idea specifically, but the whole point of building a cosmology is that it needs to be what resonates with you at your core.
In the end, all cosmologies are metaphors and stories, as existence escapes human definition and the limitations that our understanding always puts upon it. The stories we create are the vehicles for our imagination that take us beyond the physical world. We don’t want these stories to limit us, but to help carry us forward. It’s important not to get too wrapped up in our cosmology, but to let it transport us.