... The third root is found in Asgard among the gods, near the sacred fountain of Urd the norn of the past, where the gods sit in judgment, riding thither daily over the Bifrost bridge—i.e. the rainbow.  At this fountain dwell the three norns Urd (the Past), Verdande (the Present), and Skuld (the Future), and dispense the destinies of men.  They weave the web of men's lives.  It is a web of golden thread from east to west, from the radiant dawn to the glowing sunset of man's horizon.  The woof of this web is fixed in the far north, but the web woven by Urd and Verdande is torn into pieces every evening by Skuld.  The branches of Ygdrasil spread over the whole world and aspire above heaven itself.  An eagle is perched on the topmost bough, and between his eyes a hawk.  A squirrel called Ratatosk runs up and down the tree seeking to cause strife between the eagle and Nidhug.  Four stags leap beneath its branches, and feed on its buds.  Two swans swim in the Urd fountain, and everything placed therein becomes as white as the film of an egg-shell.  The norns draw water from the spring, and with it they sprinkle Ygdrasil in order that the boughs may continue green in spite of the destructive agencies that constantly assail it.  Honey-dew falls from Ygdrasil, and is food for the bees.  Odin hung nine nights on this tree and offered himself to himself. (Chambers's Encyclopaedia, v.9, 1893)