Phlegethon does not lie placidly in a riverbed, as painters love to show it, with kindly orange flames reaching half the height of a soldier at parade rest. It burns through the depths of the land and to the roof of the sky. There is no bridge to cross it, and no ferry, for it stretches from beneath the ground to the highest reaches of the heavens in a burning wall that will admit nothing and consumes everything, material or eternal. If I had a pot of the Alkahest here, I could try the old philosophical puzzle of two forces in perfect opposition, each defined by its absoluteness—and perhaps if I did, the world would end around me.