Having read an excerpt of “To Build a Fire”, why do you think Chris McCandless enjoyed reading Jack London’s work? Why would he say, “Jack London is King”?

Jack London not only spent a huge amount of time in the Yukon, he often lived off the land. I don't know what excerpt you are referring to, but London often depicted man's struggle against nature..... survival. Chris was attempting to survive on his own.... to live off the land. London would have been seen as a hero.