“In Jotunheim, the home of the giants, is Mimir’s well. It bubbles up from deep in the ground, and it feeds Yggdrasil, the world-tree. Mimir, the wise one, the guardian of memory, knows many things. His well is wisdom, and when the world was young he would drink every morning from the well, by dipping the horn known as the Gjallerhorn into the water and draining it.”