Odin’s quest for wisdom is never-ending, and he is willing to pay any price, it seems, for the understanding of life’s mysteries that he craves more than anything else. On one occasion, he hanged himself, wounded himself with his spear, and fasted from food and drink for nine days and nights in order to discover the runes.
On another occasion, he ventured to Mimir’s Well – which is surely none other than the Well of Urd – amongst the roots of the world-tree Yggdrasil. There dwelt Mimir, a shadowy being whose knowledge of all things was practically unparalleled among the inhabitants of the cosmos. He achieved this status largely by taking his water from the well, whose waters impart this cosmic knowledge.
When Odin arrived, he asked Mimir for a drink from the water. The well’s guardian, knowing the value of such a draught, refused unless the seeker offered an eye in return. Odin – whether straightaway or after anguished deliberation, we can only wonder – gouged out one of his eyes and dropped it into the well. Having made the necessary sacrifice, Mimir dipped his horn into the well and offered the now-one-eyed god a drink.
The most general and obvious message of this tale is that, for those who share Odin’s values, no sacrifice is too great for wisdom. The (unfortunately fragmentary) sources for our current knowledge of the pre-Christian mythology and religion of the Norse and other Germanic peoples are, however, silent on exactly what kind of wisdom Odin obtained in exchange for his eye. But we can hazard a guess.
The fact that Odin specifically sacrificed an eye is surely significant. In all ages, the eye has been “seen” as a poetic symbol for perception in general – consider the astonishing number of expressions, both in everyday usage and in the works of the great canonical poets, that use vision as a metaphor for perceiving and understanding something. Given that Odin’s eye was sacrificed in order to obtain an enhanced perception, it seems highly likely that his pledge of an eye symbolizes trading one mode of perception for another.
What mode of perception was exchanged for what other mode, then? The answer to this question lies in the character of Mimir. Mimir, whose name means “The Rememberer,” is the divine animating force within cultural/ethnic memory. His wisdom is the wisdom of the traditions that the heathen Germanic peoples held to be sacred. As in the tale of Odin’s discovery of the runes, in which he sacrificed what we might call his “lower self” to his “higher self,” so Odin did in the tale of his relinquishing an eye: he exchanged a profane, everyday mode of perception, beleaguered with countless petty troubles, for a sacred mode of perception, in which the world reveals itself to be divine, the very flesh of the gods, constantly enacting the stories of which the gods are the actors, shimmering with meaning and wonder.
Looking for more great information on Norse mythology and religion? While this site provides the ultimate online introduction to the topic, my book The Viking Spirit provides the ultimate introduction to Norse mythology and religion period. I’ve also written a popular list of The 10 Best Norse Mythology Books, which you’ll probably find helpful in your pursuit.
 Bauschatz, Paul C. 1982. The Well and the Tree: World and Time in Early Germanic Culture.
 The Poetic Edda. Völuspá, stanza 28.
 Snorri Sturluson. The Prose Edda. Gylfaginning 15.