The novella is one of the most-translated books in the world and has been voted the best book of the 20th century in France. Translated into 300 languages and dialects selling nearly two million copies annually, and with year-to-date sales of over 140 million copies worldwide, it has become one of the best-selling books ever published. After the outbreak of the Second World War, Saint-Exupéry escaped to North America. Despite personal upheavals and failing health, he produced almost half of the writings for which he would be remembered, including a tender tale of loneliness, friendship, love, and loss, in the form of a young prince visiting Earth. An earlier memoir by the author had recounted his aviation experiences in the Sahara Desert, and he is thought to have drawn on those same experiences in The Little Prince. Since its first publication, the novella has been adapted to numerous art forms and media, including audio recordings, radio plays, live stage, film, television, ballet, and opera.