Sophie's World (Norwegian: Sofies verden) is a 1991 novel by Norwegian writer Jostein Gaarder. It follows Sophie Amundsen, a Norwegian teenager, who is introduced to the history of philosophy as she is asked "Who are you?" in a letter from an unknown philosopher. The nonfictional content of the book aligns with Bertrand Russell's The History of Western Philosophy. Sophie's World became a best-seller in Norway and won the Deutscher Jugendliteraturpreis in 1994. The English translation was published in 1995, and the book was reported to be the best-selling book in the world that year. By 2011, the novel had been translated into fifty-nine languages, with over forty million print copies sold. It is one of the most commercially successful Norwegian novels outside of Norway, and has been adapted into a film and a PC game. Plot summary Sophie Amundsen is a 14-year-old girl who lives in Lillesand, Norway. The book begins with Sophie receiving two messages in her mailbox and a postcard addressed to Hilde Møller Knag. Afterwards, she receives a packet of papers, part of a course in philosophy. Sophie, without the knowledge of her mother, becomes the student of an old philosopher, Alberto Knox. Alberto teaches her about the history of philosophy. She gets a substantive and understandable review from the Pre-Socratics to Jean-Paul Sartre. In addition to this, Sophie and Alberto receive postcards addressed to a girl named Hilde from a man named Albert Knag. As time passes, Knag begins to hide birthday messages to Hilde in ever more impossible ways, including hiding one inside an unpeeled banana and making Alberto's dog, Hermes, speak. Eventually, through the philosophy of George Berkeley, Sophie and Alberto figure out that their entire world is a literary construction by Albert Knag as a present for Hilde, his daughter, on her 15th birthday. Hilde begins to read the manuscript but begins to turn against her father after he continues to meddle with Sophie's life by sending fictional characters like Little Red Riding Hood and Ebenezer Scrooge to talk to her. Alberto helps Sophie fight back against Knag's control by teaching her everything he knows about philosophy, through the Renaissance, Romanticism, and Existentialism, as well as Darwinism and the ideas of Karl Marx. These take the form of long pages of text, and, later, monologues from Alberto. Alberto manages to concoct a plan so that he and Sophie can finally escape Albert's imagination.