De Novo

I ween that I hung on the windy tree,
    Hung there for nights full nine;
With the spear I was wounded, and offered I was
    To Odin, myself to myself,
On that tree that none may ever know
    What root beneath it runs.

Poetic Edda, “Hovamol” (translated by Henry Adams Bellows, via Joseph Campbell: Primitive Mythology

Odin (aka Wotan), the Zeus-like Ruler of the Gods in Norse mythology, in order to retrieve sacred wisdom from the Underworld, sacrifices himself on the World Tree, Yggdrasil,

whose shaft was the pivot of the revolving heavens, with the World Eagle perched on its summit, four stags running among its branches, browsing on its leaves, and the Cosmic Serpent gnawing at its root… It is the greatest of all trees and the best, the ash where the gods give judgment every day. Its limbs spread over the world and stand above heaven. Its roots penetrate the abyss. And its name, Yggdrasil, means “The horse of Ygg”, whose other name is Odin.