The universe of the Mongols can be visualized as a circle, not only in the
three dimensions, but also in time itself. Everything has a circular
motion, the path of the sun from day to day, the cycle of time from year to
year, and the cycle of all living spirits as they return to the earth to
live again and again. Intersecting the circle are the axes of the four
direction and the axis of the center of the world going up to the upper
world beyond the eternal heavens and going down beyond Mother Earth to the
lower world. Superimposed on this is the image of the universe as seen
through the vision of shamanic journeys, by which the shaman can climb the
world tree or fly to the upper world, or travel down the spirit river to
the entrance to the lower world in the north, or simply find a tunnel in
the earth to travel below.