There are three characters in "To Build a Fire," an unnamed man, a dog, and the cold. The man and dog are walking to another camp in weather that is seventy-five degrees below zero. They must battle nature to succeed, but nature in the form of extreme cold defeats the man, and readers watch him as he slowly freezes to death. Having been in the Klondike, London knew that first a person's face, feet, and hands freeze, then the legs and arms, and then the trunk of the body. Before he or she actually dies, a freezing person goes to sleep where the process of freezing is completed, so freezing is considered one of the better ways to die, though the people who assume this have not actually frozen to death.
London has been considered a literary naturalist, which is a technical term that means an author tries to be totally objective and scientific about the characters in a story. That is the reason London does not give the man in "To Build a Fire" a name. The man is a member of his species whom London watches as he struggles with the cold. The author merely reports what happens and does not draw conclusions. It is up to the reader to figure out what London may be trying to tell them.
Naturalism was influenced by Darwin's theory of natural selection, and London was an enthusiastic Darwinian. It is important to understand that Darwin's theory of survival of the fittest does not necessarily relate only to strength. In the twentieth century, fascists like Hitler misinterpreted the theory of survival of the fittest and applied it to people in general. The theory of social Darwinism implies that some people are better than others, so the better people deserve to survive while the people who are less fit should be eliminated. This sort of misguided thinking led to the murder of millions of people during the Nazi regime.
What Darwin actually proposed was the idea that a species best adapted to its niche in nature will be more likely to survive than a species that is not so well adapted. For example, natural selection has caused many animals to develop camouflage coloring so that predators cannot see them or eat them. Camouflage is a trait that makes the animals more likely to survive and has nothing to do with strength.
Survival of the fittest is the main theme in "To Build a Fire." The man is stronger and presumably smarter than the dog, yet the man is afflicted with "hubris" (too much pride in his abilities), and he fails to overcome nature. London seems to be saying that people have relied on technology like fire so much that they are no longer able to survive in the wild without technology. While the man cannot survive without fire, the dog can. The dog is much closer to its ancestral way of being than the man is. It appreciates technology like fire, but it is not a necessity for its survival. The man does not realize how much he depends on technology until it fails him. He is not fit to survive in the cold, but the dog, who seems to be a lower animal, can stay alive. Thus, London, like many naturalist writers, shows readers that they are not as superior to other animals as they may think. He attacks the pride many people take in their supposed superiority and humbles them. Most people have character or personality flaws that can result in problems. One of the flaws that the man has is that he has no imagination. London says,
The trouble with him was that he was without imagination. He was quick and alert in the things of life, but only in the things, not in the significance. Fifty degrees below zero meant eighty-odd degrees of frost. Such fact impressed him as being cold and uncomfortable, and that was all. It did not lead him to meditate upon his frailty as a creature of temperature, and upon man's frailty in...
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