One thing we know about Odin is that he received human sacrifices. His victims were often hanged from trees, about which more later. This carving on a Viking age stone from Gotland seems to show two sacrifices, one that may be a child, laid out on a stone for slaughter, and a warrior with shield who has been hung from a bent tree; when the tree is released it will lift him into the air and strangle him. Over them hovers the interlaced triple triangle of the Valknut, or dead man's knot, which is a symbol of Odin and probably indicates that the sacrifices are for him.
Odin made sacrifices of his own. For one drink from the spring that flows forth at the foot of Yggdrasil he gave up one of his eyes, but the water from that sacred spring gave him great wisdom. He was called the Far-Seeing, and the All-Knowing. His companions were ravens, which are emblems of both wisdom and slaughter, another connection between Odin's sovereignty and the land of the dead.
Adam of Bremen, writing around 1070 AD, gives us an important clue to Odin’s identity. Wotan, he wrote, id est furor. “Wotan, that is, madness.” Among Odin’s followers were the berserks of the Viking era, men who fought in a state of frothing rage beyond pain or fear. Odin was the god of poets and gave them their inspiration. He was the master of the runes, which were used in foretelling the future. An obscure Norse poem tells us the story of how he acquired his rune mastery:
Wounded I hung on a wind-swept treeWhat kind of god acquires his wisdom by hanging for nine nights on a tree?
For nine long nights,
Pierced by a spear, pledged to Odin,
Offered, myself to myself
The wisest know not from whence spring
The roots of that ancient rood.
They gave me no bread,
They gave me no mead,
I looked down;
with a loud cry
I took up runes;
from that tree I fell.
A shaman god. Odin, in the stories that come down to us, acts much like a shaman, specifically a Siberian or Lapp shaman. Shamans, the most ancient human religious practitioners, enter into a trance state in which their spirits leave their bodies to journey through other planes or realms; often the place they visit is imagined as the realm of the dead. From their journeys they bring back knowledge, especially knowledge of the future or of how to cure diseases. Shamanic lore is woven all through Norse myth, from Freya’s cloak of feathers to Odin’s eight-legged steed -- both were conveyances used by shamans in their spirit journeys. The Norse cosmos was centered on a great ash tree, Yggdrasil, whose roots and branches connected the nine worlds where humans, gods, giants and others lived. This is the cosmos of the Siberian shamans, and they imagined themselves climbing up the world tree as they entered the spirit realm. Sometimes they climbed trees or wooden poles as part of their rituals. They called these trees their spirit horses. Yggdrasil means “the steed of Odin,” so the axis of the world as the Norse saw it was the pole their shaman god climbed to reach knowledge.
Here is the connection between Odin and all-knowing and Odin the god of death, for like a shaman he must travel the spirit road to acquire his wisdom.
Shamanic ecstacy was widely seen as a sort of temporary madness, and the overall sanity of its practitioners was suspect. This notion carried over into other forms of ecstasy, for example in the tradition that makes poetic inspiration a kind of madness. This is why Odin, the shaman, is the patron of poets and berserks – all forms of ecstasy fall under his purview.
The worldview of the Siberian shamans was not optimistic. They believed that most or all of life was governed by impersonal forces beyond the control even of gods, and the that the shaman’s main role was to discover what fate those forces had decreed. Sometimes, by heroic effort, a shaman could avert an illness or discover that some catastrophe had been sent by an angry god who might be placated. Mainly, though, they were discoverer, not shapers. Death meant passage to a shadowy realm where spirits had even less freedom than living humans. The gods themselves would in the end be defeated and destroyed, their doom already decreed.
So far as we can tell, the ancient Germans had a similarly gloomy cosmology. Into Valhalla, the Hall of the Slain, Odin gathered dead heroes and feasted them so that they would fight for him in the last battle. This was the best sort of afterlife the Norse could imagine, and we hear little in their legends about the fate of dead farmers or housewives. But the afterlife of the heroes was shadowed by the end they knew was coming: Ragnarök, when Fenris the Great Wolf would snap his chains and swallow the sun, the gods would be overwhelmed by monsters and demons, and the dead heroes would meet their final end. Perhaps, though, some of the tales hint, the world would then be remade, and perhaps that future world would be better than the violent, cruel world of the Viking age.