One of the Norse tales that has fascinated me the most has been the story of Odin and Yggdrasil, the world tree. It seems such a strange story, similar to the Christian myth, and more transcendental and less earthy than I normally expect from the sagas.

Here is a precis from a site on Norse Mythology:

Amongst Odin's gifts to us, his children, was the greatest of all: the gift of writing. To accomplish this Odin hung himself upside down upon the World Tree, the gigantic ash Yggdrasil ( a compound meaning "terrible horse"). After nine days of fasting and agony, in which "he made of himself a sacrifice to himself", he "fell screaming" from the tree, having had revealed to him in a flash of insight the secret of the runes. Their initial manifestation took the form of eighteen powerful charms for protection, increase, success in battle and love-making, healing, and mastery over natural causes.