The rhyme scheme of the poem is: a, b, a, a ; b. c, b, c, b.
The contrasting ideas of ‘fire’ and ‘ice’ are presented using this rhyme scheme. He mentions that both fire and ice are probable ends of this world. While he talks about how fire represents desire and can therefore be a cause of the end of the world, he also mentions ice in between to symbolize that the cold and indifferent attitude towards one another will also be enough to end the world. In the second stanza, he says that he knows of enough hate in the world that even destruction through ice would be sufficient to bring about the end of the world.
