According to Norse belief, an immense, unseen tree called Yggdrasil stretched from the vault of heaven to the depthd of hell. A dragon named Nidhoggr gnawed perpetually at the roots, seeking to destroy the order of creation, but the order had a battalion of defenders. Three godlike beings called Norns sat calmly near the dragon at the roots, spinning the threads of mortal fate. Stags browsed at the tree and watered the earth with dew from their antlers. A goat that chewed the tree's bark provided mead as milk for mortal heroes who would rid the world of the dragon race. Of the birds that perched in Yggdrasil's branches, the greatest was the eagle-- a steadfast dragon enemy that sang forever of creation and destruction.