Answer:
The theme in “To build a fire” is that ”Never underestimate Nature” and “Don’t be afraid for help”. In the story the man was traveling alone in freezing temperature and had no one to help him if in case soemthing happens. He was freezing and when he tried to build a fire to warm up, he couldn’t becuase he couldn’t concentrate, now when he finally did succeeded, there was a tree and the snow on it was starting to melt becuase of the fire below and eventually it collapesed putting out the fire. By this point the man had no more matches and couldn’t build another fire and he froze to death. If the man wasn’t alone, he might’ve survived becuase there was someone else there to help him and help him recover. By thinking he’s a man superior than others and thinking that he can withstand freezing tempertures, ironicaly, he died to the cold.