Norse cosmology

The cosmology of Norse mythology has "nine homeworlds" or "nine realms", unified by the world tree Yggdrasil. Mapping the nine worlds escapes precision because the Poetic Edda often alludes vaguely. The Norse creation myth tells how everything came into existence in the gap between fire and ice, and how the gods shaped the homeworld of humans.

A cosmic ash tree, Yggdrasil, lies at the center of the Norse cosmos. Three roots drink the waters of the homeworlds, one in the homeworld of the gods, the Æsir, Asgard, one in the homeworld of the humans, Midgard, and one in the homeworld of the dead, Helheim. Beneath the root in the world of the frost giants is the spring of Mímir, whose waters contain wisdom and understanding.

The root in the Æsir homeworld taps the sacred wellspring of fate, the Well of Urðr. The tree is tended by the Norns, who live near it. Each day, they water it with pure water and whiten it with clay from the spring to preserve it. The water falls down to the earth as dew.

Animals continually feed on the tree, threatening it, but its vitality persists evergreen as it heals and nourishes the vibrant aggression of life. On the topmost branch of the tree sits an eagle. The beating of its wings cause the winds in the world of men. At the root of the tree lies a great dragon, Niðhǫggr, gnawing at it continuously, together with other unnamed serpents. The squirrel Ratatoskr carries insults from one to the other. Harts and goats devour the branches and tender shoots.

In the beginning, there were two regions: Muspelheim in the south, full of fire, light and heat; and Niflheim in the north, full of arctic waters, mists, and cold. Between them stretched the yawning emptiness of Ginnungagap, and into it poured sparks and smoke from the south and layers of rime and glacial rivers from the north. As heat and cold met in Ginnungagap, a living jǫtunn, Ymir, appeared in the melting ice. From his left armpit, the first man and woman were born. From his legs, the frost jötnar were born, making Ymir the progenitor of the jǫtnar. Most sources identify Ymir's oldest son as Þrúðgelmir, who bore Ymir's grandson, Bergelmir. The other jǫtnar are usually unnamed. Ymir fed on the milk of the cow Auðumbla. She licked the blocks of salty ice, releasing Búri.

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