I think that the authors theme is about a man who decides to travel alone in a hostile environment and the power of nature is greater than man himself.
1. When the man decided to build a fire underneath a tree – this is an example of nature vs. man. When the man decided that building the fire under the tree was a good idea, or even a bad mistake to build it under there. He would pull the branches from the tree and they would drop into the fire. Every time he would pull a branch from the tree he would cause a slight imperceptible agitation to the tree in which the freight of snow on the branches all came down onto the nicely built fire. Nature had over powered the man in a way that he couldn’t overpower nature.
2. the law that no man must travel alone in the Klondike after fifty below – when the old timer had warned the man about the law, he went ignoring the law even though he knew what might be the consequences. That action shows that the man does not respect the powers of the natural world.
3. man starts a battle he cannot win – the odds are not in his best favor as the story goes on. It almost seems as nature is punishing him for disobeying the old timers warning about the law as he continues his adventure throughout the Yukon. He is first punished with the coldness of the Yukon, which then turns into numbness of his fingers and outer extremities. Frostbite soon takes over his body and begins affecting his body and ways of doing skills to survive. He falls into the water and wets his moccasins which then makes his feet even more cold, causing his own body to freeze. He is unable to start and keep a fire burning, as he makes a fire under a tree and the tree’s branches freight burns out the fire. He soon is unable to feel any part of his body and everything begins to slowly feel warm and that is when nature over powered man and he did not win the battle.