Sophie
Sophie is the main character in Sophie's World. She is the creation of Albert Knag in order to amuse his daughter Hilde. Along with Alberto Knox, Sophie is a part of Hilde's birthday present. Sophie is to turn fifteen on June 15, the same day as Hilde. Sophie is clearly created as somewhat of a counterpart to Hilde, but she and Alberto manage to escape Albert Knag's mind and gain an existence of their own. Throughout the book Sophie learns how to be a philosopher. Early on she ponders the questions that Alberto gives her and has good thoughts about them but she really does not know how to answer them. However, as the lessons continue Sophie's mind becomes extremely acute. She remembers everything that Alberto has taught her because it is all- important to her and she is able to come up with interesting philosophical propositions of her own. Although Alberto knows more about philosophy than Sophie does, she fares better when they enter their new lives as beings of spirit existing within Hilde's world. Perhaps this is because Alberto has trained Sophie and so she has not only picked up what he has tried to teach her but also been critical of him. She was given the best education possible and uses it to the best of her abilities. Sophie figures out that she and Alberto can have an effect on Hilde's world when she dares to think that they can. Alberto disagrees with her, but Sophie has learned from him that the opinions of others should not have the power to dissuade someone from an action they believe in. Sophie is also extremely individualistic. She learns from Alberto but she thinks on her own. She is critical of him, her mother, and her friend Joanna. Sophie acts with conviction and thinks things through before she does them and that makes it difficult to fault her. After all, she is only a fifteen year old girl, and she acts extremely mature for her age.
Alberto
Alberto Knox is Sophie's philosophy teacher. He is the ideal teacher, and never stops learning. Alberto is dynamic, and he is just as willing to learn from Sophie as she is from him. In the beginning of the book it is most often he who must explain things to her, but by the end they are equals and treat each other that way. Alberto cares about Sophie and orchestrates their escape. He is also extremely pensive and always thinks things through. Many times, Sophie rushes ahead with her thoughts and Alberto points out to her that she has not stopped to consider something. He is a great example of the fact that thinking things through, even if it sometimes takes a while, is preferable to jumping to conclusions. And Alberto is also humble. He is a true philosopher because he does not believe that his knowledge is all that great and so when he makes a mistake he is quite willing to learn from it. Throughout the book it is difficult to see much change in his character, but he definitely becomes livelier as Sophie begins to get better at philosophical thinking. That could be because as a philosopher he values the company of one who can teach him above all else. Alberto also has a firm belief in reason, he uses his mind to control situations that he does not have control of. For example, he realizes that if they are simply thoughts in Albert Knag's brain, then perhaps they can utilize Hilde's father's unconscious to help bring about their escape. Even in the face of unbelievable circumstances Alberto holds on to the one thing that makes him human—his ability to think.
Hilde
Hilde Møller Knag is Albert Knag's daughter. She is the reason that Sophie and Alberto were created in the first place. Hilde bears a strong resemblance to Sophie in that she learns to think philosophically alongside Sophie. She is compassionate, because she feels for Alberto and Sophie, even though they appear to be fictional characters. Hilde believes that Sophie exists somewhere, although she cannot explain how. At age fifteen, she still retains enough belief in the mysterious nature of life and the inexplicable mysteries that surround us to hold a firm belief in something that would be characterized as impossible. But it turns out that, although she does not know it, Hilde is correct—Sophie and Alberto do "exist" in some strange way. Hilde represents that sort of person who can think and reason well but also is willing to believe in what she feels to be true regardless of what anyone else thinks. So, in some ways, Hilde represents that ideal reader for Gaarder's book. Sophie's World is designed to be both a novel and a history of philosophy, and someone like Hilde would understand and think about the philosophical ideas that are put forth but would also be partial to the fantastical aspects of the story.
Albert Knag
Albert Knag is Hilde's father. He has the creative genius to write a book in which his characters become aware of their role as characters in the book. What's more, he carries on direct interaction with those characters even though they are simply figments of his own imagination. Perhaps it was Albert Knag's brilliant construction of Sophie and Alberto that allowed them to gain some sort of an existence for themselves. He created Alberto very much in his own image. Albert Knag is a philosopher first and foremost. His book about philosophy is a gift of love to his daughter because he could not imagine anything better than giving her the same love and wonder for the world that he has. Albert has a great sense of humor that comes out in his interactions with Sophie and Alberto. However, he is also extremely indulgent in his writing. Hilde plays her trick on him to show him what it would be like to be manipulated in the way that he controls Sophie and Alberto. Albert learns from his daughter and realizes that perhaps he went a bit too far in his story, but we can forgive him for that, because his mistakes were for all the right reasons.
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