Robert Frost's "Fire and Ice" combines a simple rhyme scheme with a rather dark message. The entirely of the poem reads as follows:
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.
The poem features a rhyme scheme of ABAABCBCB, and the end rhymes themselves are fairly simple (e.g., fire, desire; hate, great). The basic sound and rhythm of the poem belie a darker meaning, though. The tone of the poem sounds rather casual and conversational, but when we look closely at what the speaker is contemplating, we see the contrast between the "sound" and the "sense," or meaning.
The speaker considers two possible ways the world could end: by burning up in a fire or by freezing in ice. He then thinks about which he would prefer, or which would be worse or better. The speaker aligns "fire" with "desire," both in rhyme and in content; he claims his experience with desire makes him think the world will end in fire. This suggests that the speaker has been figuratively burned by his desire, and he therefore imagines fire to be more painful.
On the other hand, he considers what ice might imply, too. He associates ice with "hate," and he imagines that, based on his experience with "hate," that ice would also be an appropriately painful end to existence. Basically, the speaker feels that either fire or ice could cause the apocalypse, as both desire and hate, seemingly opposite emotions, can be equally painful.