Thudd is really a cosmic tree, and a physical one, unlike the Nordic world-tree, Yggdrasil, which is an ethereal circuit that connects to a multitude of worlds. In Thudd, there is only two worlds; the waking world and the dreaming world. The waking world is understood as the physical plane, but the dreaming world to the Thuddim is equally real. It is in the dreaming world the Thuddim go into the center of Thudd to tend to the Great Spirit at the time of Darkening (cosmic winter of Thudd), when the entire people go into the Long Sleep. The nature of both worlds will be discussed extensively in the following chapters.