Sophie's World

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. The trick is performed on Midsummer's Eve, during a "philosophical garden party" that Sophie and her mother arranged to celebrate Sophie's fifteenth birthday. The party soon descends into chaos as Albert Knag lost his control over the world, causing the guests to react with indifference to extraordinary occurrences. Alberto informs everyone that their world is fictional but the guests react with rage, believing him to be instilling dangerous values in the children. When a Mercedes smashes into the garden, Alberto and Sophie use it as an opportunity to escape. Knag is so focused on writing about the car that he doesn't notice them escaping into the real world.

Having finished the book, Hilde decides to help Sophie and Alberto get revenge on her father. Alberto and Sophie cannot interact with anything in the real world and cannot be seen by anyone but other fictional characters. A woman from Grimm's Fairy Tales gives them food before they prepare to witness Knag's return to Lillesand, Hilde's home.

While at the airport, Knag receives notes from Hilde set up at shops and gateways, instructing him on items to buy. He becomes increasingly paranoid as he wonders how Hilde is pulling the trick off. When he arrives back home, Hilde has forgiven him now that he has learned what it is like to have his world interfered with. Alberto and Sophie listen as Knag tells Hilde about one last aspect of philosophy—the universe itself. He tells her about the Big Bang and how everything is made up of the same material, which exploded outward at the beginning of time. Hilde learns that when she looks at the stars she is actually seeing into the past. Sophie makes a last effort to communicate with her by hitting her and Knag with a wrench. Knag doesn't feel anything, but Hilde feels as though a gadfly stung her, and can hear Sophie's whispers. Sophie wishes to ride in the rowboat but Alberto reminds her that as they are not real people, they cannot manipulate objects. In spite of this, Sophie manages to untie the rowboat and they ride out onto the lake, immortal and invisible to all but a few. Hilde, inspired and mesmerized by philosophy and reconnected with her father, goes out to get the boat back.

In the Xiao Baosen-translated Chinese version (Simplified Chinese) published by Writers Publishing House, parts of the content related to Karl Marx were deleted according to the requirements of the Ministry of Culture of the People's Republic of China, such as the last 32 paragraphs in the Marx Chapter.[5]

• Simulated reality
• World as Myth

• Timeline of Sophie's World