In Norse* mythology, a mighty axis, or pole, ran through the universe in which the gods, giants, and heroes enacted their stormy dramas. That axis, around which all life revolved, was the World Tree, a giant ash tree called Yggdrasill.
The myths paint a complex picture of how the universe was structured around Yggdrasill. Sometimes the World Tree is described as running through nine realms, from the shadowy depths of the underworld up to the heavenly abode of the gods. At other times, the trunk of Yggdrasill is said to anchor Midgard, the world of humans, while the tree's three great roots reach down into Jotunheim, the land of the frost giants; Niflheim, the land of mist; and Asgard, the home of the gods.
Although the World Tree offered an avenue of passage from one realm to the next, the distances and dangers involved in such travel were great. The only creature that could run up and down Yggdrasill easily was a squirrel, which carried insulting messages between a fierce eagle perched in the tree's topmost branch and a dragon that gnawed at its root. Yggdrasill existed in a state of delicate balance, being endlessly destroyed and renewed.
underworld land of the dead
The World Tree was closely linked to sources of hidden or magical knowledge. Its name, which means "Odin's horse," refers to Odin* hanging himself from the tree for nine days and nights to learn secret mysteries. Near one root rose a spring whose waters provided wisdom. Odin was said to have traded an eye to drink
* See Nantes and Places at the end of this volume for further information.
this water. Another root sheltered a spring tended by the Norns, three women who determined the fate of all humans.