off the shoots.... More serpents lie under Yggdrasil's ash than
any one knows. Ofni and Svafni I know will ever gnaw at the tree's
twigs. Yggdrasil's ash suffers more hardships than men know: the hart
bites above, the side decays, and Nidhögg gnaws below.... Yggdrasil's
ash is the best of trees."

The snake and the tree are familiar in other mythologies, though in
most other cases the snake is the protector, while here he is the
destroyer. Both Nidhögg and Jörmungandr are examples of the destroying
dragon rather than the treasure-guardian. The Ash is the oracle: the
judgment-place of the Gods, the dwelling of the Fates, the source of
the spring of knowledge.

* * * * *

_Ragnarök_.--The Twilight of the Gods (or Doom of the Gods) is the
central point of the Viking religion. The Regin (of which _Ragna_
is genitive plural) are the ruling powers, often called Ginnregin
(the great Gods), Uppregin (the high Gods), Thrymregin (the warrior
Gods). The word is commonly used of the Aesir in _Völuspa_; in
_Alvissmal_ the Regin seem to be distinguished from both Aesir and
Vanir. The whole story of the Aesir is overshadowed by knowledge of
this coming doom, the time when they shall meet foes more terrible
than the giants, and fall before them; their constant effort is to
learn what will happen then, and to gather their forces together
to meet it. The coming Ragnarök is the reason for the existence of
Valhalla with its hosts of slain warriors; and of all the Gods, Odin,
Thor, Tyr and Loki are most closely connected with it. Two poems of
the verse Edda describe it: