The magic of Christmas
One of the most important themes in The Polar Express is the magic of Christmas. As the boy and the rest of the children board the eponymous Polar Express train, all of them either don't believe in or wrestle with, their feelings about believing in Christmas and Santa Claus. The boy and the rest of the children are brought to Santa's workshop, where they are exposed to Santa himself, the elves, and Santa's reindeer (as well as many other things). After their experience in the biggest symbol of Christmas, Santa's workshop, the boy and the rest of the children on the train are left enchanted and transfixed by Christmas, Santa Claus, and the Christmas season in general.
Self-discovery
Self-discovery is a significant theme in The Polar Express. Before the boy comes across the eponymous Polar Express train, he is struggling to decide whether or not he believes in Santa Claus. The train, which is a metaphor for the boy's journey of self-discovery, takes the boy and a number of other kids (some of whom also don't believe in Christmas and Santa Claus) to Santa's village where he creates gifts for people across the world. After their experience in Santa's village, where they meet Santa, the boy and the rest of the children discover quite a bit about themselves. Primarily, though, they determine that they believe in Christmas and in Santa Claus.
Companionship
Another important theme in The Polar Express is companionship. The boy who is the main character of the novel finds companionship in several people, including the train conductor, the other children on the train, and Santa Claus himself. Before that, it seems that the boy was mostly alone and had no one to confide in about his doubts about Christmas and Santa Claus. However, with the help of the conductor, the other children, and Santa Claus, the boy learns more about himself, becomes more confident, and finds people with whom he can confide. In that sense, The Polar Express sends an important lesson to readers: people need companionship to survive and thrive in a cold world.
