Odin's Tale of the Keys of Knowledge*
I am aware that I hung on the windy tree,
swung there nights all of nine;
gashed with a blade, bloodied for Odin,
myself an offering to myself,
knotted to that tree no man
knows whither the root of it runs.
None gave me bread, none gave me drink,
down to the depths I peered
to snatch up the runes with a roaring scream
and fall in a dizzied faint.
Well-being I won and wisdom too,
I grew and joyed in my growth;
from a word to a word, I was led to a word,
from a deed to another deed.
*This is from the 'Havamal'.
This is an old custom.