The listing, Sophie's World by Jostein Gaarder has ended.
"Sophie's World" is amazing, it's a philosophy course made a novel. Most people interested in the "big questions" have probably read through their lives several authors, maybe Plato's "Dialogs", Descartes, Kant; or modern ones like Nietzsche, Freud or Marx. However, by doing this (reading only some authors) its difficult to understand the evolution of the philosophical thought through the history of mankind, you are unable to compare all the different approaches to questions that have been asked repeatedly since thousands of years. This book gives you the vision, and the head start for a more profound reading of occidental philosophy. For example years ago I started Nietzsche's "Beyond good and evil", and not being able to understand why he criticized Kant I dropped the book. After reading in Gaarder's book Kant's basic ideas I finally understood the divergence of thoughts.