What is the theme in The Colour of Magic by Terry Pratchett?

Heroism is a central theme in the story. What makes a hero and how one becomes a hero is one of the key themes in the novel. The main character, Rincewind, is far from what would traditionally be considered a hero. Rincewind is not a full-fledged wizard, nor does he have any inclination toward being one. He is reluctant to help others if it means that his life will be endangered. As a result, each time Rincewind is in a dangerous situation, he reacts very selfishly.