Sophie's World is a book within a book, with the implication that perhaps such a regression could continue ad infinitum. Alberto lectures Sophie about philosophy but then we learn that the lectures are really not for Sophie but for Hilde. Yet as readers we realize that the lessons are not in fact for Gaarder's imaginary characters but for us. The very medium of the book is used to help illustrate philosophical points. Although it is quite engrossing, this is not the sort of book that one can read without being conscious of that fact. Many times what people prize in book (as in other forms of entertainment) is the ability to get lost in them. But even getting lost in Sophie's World requires knowing precisely that one is lost within the book. Gaarder constantly reminds us that we are reading a book about characters in a book a girl is reading. Besides the humorous irony that comes from such reminders, we are also forced to take the ideas of the novel seriously. Because the ideas that are put forth do not only have import within the book, and that is part of Gaarder's main point. The book itself insists that we must question what we read and attempt to better understand what Sophie and Hilde struggle with so that we can make philosophy personally relevant.
Sophie's World contains many dreams, some of which are not easily differentiated from reality. In fact, dreams are used quite effectively to question our sense of reality. Sophie obtains items that belong to Hilde in he dreams. Of course, since Sophie's dreams are orchestrated by Hilde's father, that does not seem strange. However, the fact that Hilde cannot find the items that Sophie comes across suggests that strange things are happening. Hilde dreams that Sophie speaks to her before her father comes home and at the end of the book that is exactly what happens. Alberto also tells Sophie (and therefore Albert tells Hilde) about Freud and theories of dreams as wish fulfillment and links to the unconscious. As a literary device, the dreams in the book provide foreshadowing. However, their role is greater than simply to alert the reader to future occurrences. The dreams themselves bring into question our free will and our possibilities of understanding the world.