[twilight of the gods]. The day of doom, when the present world and all its inhabitants will be annihilated. Vidar of Vali will survive the conflagration, and reconstruct the universe on an imperishable basis. (Scandinavian mythology.)
And Frithiof, mayst thou sleep away Till Ragnarok, if such thy will.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894