Sophie's World (Sofies verden in the original Norwegian) is a novel by Jostein Gaarder, published in 1991. It was originally written in Norwegian, but has since been translated into English (1995) and at least 53 other languages. It sold over 30 million copies and is one of the most successful Norwegian novels outside Norway.
Mostly consisting of dialogues between Sophie Amundsen and a mysterious man named Alberto Knox, interwoven with an increasingly bizarre and mysterious plot, Sophie's World acts as both a novel and a basic guide to philosophy.