" Yggdrasil is the Tree of Life,’ he says. ‘Its branches cover the world and stretch up to the sky. But it has only three roots. One is submerged in the waters of the Pool of Knowledge. Another in fire. The last root is being devoured by a terrible creature. When two of its roots have been consumed by fire and beast, the tree will fall, and eternal darkness will spread across the world. "

― Tan Twan Eng , The Garden of Evening Mists