Some say the world will end in fire,
Some say in ice.
From what I've tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To say that for destruction ice
Is also great
And would suffice.

 Frost’s ironic understatement reminds us that it doesn’t really matter how the world is brought down. “Hot” passion and “cold” hatred can be equally destructive, and once they’ve done their work, there’s no turning back. 
 Older ideas here prevail–more medieval associations: The idea of destructive punishments that fit the crime: Hellfire or Hel as ice? The world’s destruction is figured as a result of human impulses taken to an extreme. Anthropocentric! And more, that it would be “great” to go in this way–such a wonderfully flat word, suggesting (along with “From what I’ve tasted of desire” that the form of the world’s end we get ought to be the one that involves us revelling in our hot lusts or cold antagonism. The implication is that we WANT the end to come in one way or the other. We wouldn’t want to turn back–the end would “suffice” us.
Fire and Ice