In the coal fields of West Virginia there are abandoned mines—their entrances long closed, the nearby towns long impoverished—that have caught on fire. These fires are impossible to put out; slowly they burn through the seams of coal, thirty or forty years. How wonderful if the writer of a book should happen on a topic with such longevity! At times he'll wish he'd picked some simpler theme, something he could strip-mine in a season, or something that would flash up and die down in a matter of months so that he could publish and get on. Get on with what, though? Better to be enveloped in a matter that darkly feeds itself with hidden fires; better not to know fully where the veins of fascination lead, but to trust that they will slowly give up their heat in recompense for attention paid.