The Voyage of the Dawn Treader is about our spiritual journey, and the transformation we experience along the way—nowhere is this clearer than in the changes in Eustace Scrubb. As we learn in the first sentence: “There was a boy called Eustace Clarence Scrubb, and he almost deserved it.” And in the last, “…back in our own world everyone soon started saying how Eustace had improved, and how ‘You’d never know him for the same boy’.”
Lewis believed that humans could continue to improve spiritually until they became something “like God” or could devolve spiritually until they ceased to be human at all. In Dawn Treader we see both the potential pitfalls of the spiritual life and the potential victories. And all of them, it turns out, have one thing in common: Aslan.