From Hlidskjalf, his "High Seat with a view", Odin could survey all of his world and much of others. But this was just one instance of his powers of vision and wisdom. Early in his reign over Valhalla, the Allfather believed that he needed more ability to see and understand. In short, he sought a sort of omniscience. He consulted the well of Urd, where Mimir's head offered advice to those willing to consult him. The well itself lay at the foot of Yggdrasil, near the abode of the Norns.

Those three wise and knowing women were something like their Greek counterparts, the Fates. There is little indication that they were divided by Mother, Maiden and Crone though. The Norns, were divided by name, and provenance as they wove the skein of fate. Urd most likely controls the overall weaving, as she is the Norn of the past.

Verdandi adds the weaves of individual Wyrd or fate into the tapestry where they would await their place at the hands of Urd. And finally, there is Skuld, the prophetess of the three, the Norn of what will come to pass. Her wide-ranging vision would find the proper threads to pass back into the present or what was transpiring in the moment. This mastery of fate itself made them some of the most powerful entities in existence. Even gods such as the Aesir and Vanir can not control fate. But they also refused to tell any god of his own thread within the weave.

Thus, denied the wisdom of the Norns concerning things his own fate might touch upon, Odin consulted Mimir's head, and even plucked his own eye out as an offering to that wisdom. A possible side effect of that act of sacrifice was to give him a constant presence in the waters of Urd that contained much of the wisdom that passed through that eldritch area. But the main wisdom he gained, was that there were mighty powers he might access with an even more drastic offering.

And so Odin, having sacrificed an eye, pierced himself through the side of his chest with the magical spear Gugnir. Then, deeply wounded he hung himself upside down from the branches of Yggdrasil, the Tree of Life. As his blood slowly drained, he grew weaker and his mind wandered farther and farther. For nine days he hung as a sacrifice, to himself and to wisdom. On the ninth day a vision formed before his fading eyesight. He groped for that vague shimmering force, and awoke clutching the runes of the Elder Futhark, along with an instinctive knowledge of their use. Later he would consult Freya and learn another magical art, that of Seidr, or a form of shamanism. It is likely that the practice of Seidr deepened his understanding and made him possibly the strongest practitioner of runic lore and magic. And it is from Odin that certain men learned of the runes and their usage.

Odin's Quest for Wisdom