The gigantic ash-tree Yggdrasil supports the universe. One of its roots goes up to Asgard, & beside it lies the sacred Urda's well, guarded by the 3 Norns, who, like the Greek Fates, allot lifespans & destinies to men. A serpent gnaws at the roots of Yggdrasil; when he gnaws all the way through, the tree & the universe will topple.
a) Sacred Tree Structure
b) Yggdrasil's Roots
c) Norns' Guardianship
d) Serpent's Menace
