Besides being god of wisdom, Odin was god and inventor of runes, the earliest alphabet used by Northern nations, which characters, signifying mystery, were at first used for divination, although in later times they served for inscriptions and records.
Just as wisdom could only be obtained at the cost of sacrifice, Odin himself relates that he hung nine days and nights from the sacred tree Yggdrasil, gazing down into the immeasurable depths of Nifl-heim, plunged in deep thought, and self-wounded with his spear, ere he won the knowledge he sought.
“I know that I hung
On a wind-rocked tree
Nine whole nights,
With a spear wounded,
And to Odin offered
Myself to myself;
On that tree
Of which no one knows
From what root it springs.”
Odin’s Rune-Song (Thorpe’s translation)
When he had fully mastered this knowledge, Odin cut magic runes upon his spear Gungnir, upon the teeth of his horse Sleipnir, upon the claws of the bear, and upon countless other animate and inanimate things. And because he had thus hung over the abyss for such a long space of time, he was ever after considered the patron divinity of all who were condemned to be hanged or who perished by the noose.
After obtaining the gift of wisdom and runes, which gave him power over all things, Odin also coveted the gift of eloquence and poetry, which he acquired in a manner which we shall relate in a subsequent chapter.
Myths of the Norsemen by H. A. Guerber