Nine Nights on the Tree

The stretch of Hávamál known as the Rúnatal is spoken in the first person, and it is the strangest passage in a poem otherwise full of practical advice. He hung on a wind-torn tree for nine nights, wounded with a spear, given to Odin, himself to himself, on a tree whose roots nobody knows. No bread was handed up to him and no horn of drink. He looked down, took up the runes screaming, and fell back from there. The sources make the sacrificer and the sacrifice one person and do not explain how that works.