In "How to Build a Fire Jack London characterizes a man and his dog traveling a Yukon trail. The man sets off with his dog despite grave warnings from a village elder that traveling at “50 is extremely dangerous. The dog is the stronger and the instinctively smarter character in the story. The dog may not understand the reasoning behind its frailty, but it listens to its instinct non the less. The man with all his worldly knowledge really believes he is above nature, while the dog follows his instincts and out lives the man in the end.
The story begins with the man and the dog traveling in to the Yukon at dangerously low levels of temperature. The man knows that it is tremendously cold, but "it made no impression on the man. (London 223) The dog "knew that is was no time for traveling. It's instinct told it a truer tale than is told to the man by the man's judgment. (London 224) This line is a powerful foreshadowing of the terrible events to come. The dog listens to its instinct and feels or sub-consciously knows the danger it faces, while the man believes he is above the danger. "The dog did not know anything about thermometers. Possibly in the brain there was no sharp consciousness of a condition of very cold such as was in the man's brain. But the brute had its instinct. (London 224)
The man realizes that there is a possibility that he may fall through the ice; as such he puts the dog in front. After walking for a while the dog falls through the ice a few inches and gets its paws wet. The dog quickly begins to bite the ice from its feet without a real understanding of exactly what it was doing. "This was a matter of instinct. To permit the ice to remain would mean sore feet. It did not know this. It merely obeyed the mysterious prompting that arose from the deep crypts of its being. (London 227)