BOOK REVIEW / NOVEL : Characters Tread Murky Line Between Fantasy, Reality : SOPHIE’S WORLD: A Novel About the History of Philosophy <i> by Jostein Gaarder</i> ; Farrar Straus and Giroux $19, 403 pages

Dear Mr. Gaarder:

Or would you prefer Author-God, Master of the Universe or Sir? That’s some trick, using the garish rubric of a novel to publish a textbook on philosophy (yes, we all know from Newsweek and Publisher’s Weekly--pretty impressive publicity for an obscure Norwegian writer--that you teach high school philosophy). Sure, it may be selling across Europe like a cheap leather jacket (320,000 copies in Germany alone), but the Europeans go in for your kind of artifice, your kind of intellectual back flips.

Here in the United States we like a story; we like to feel good when we put a book down, to stand on firm ground: You’re the writer, they’re the characters, we’re the readers. We finish the book. Then we go to work or walk the dog or watch the news. You go away.

But you weren’t thinking about that when you wrote your bestseller, now were you? You weren’t thinking about the experience of reading this book because you were too busy moving your characters around your game board. Well you know what, Mr. Gaarder? I don’t trust you one bit. I don’t believe the book ends the way you end it. If you are interested in how it really ends, you can contact me, at. . . . On second thought, you can’t contact me. A reader must keep himself aloof from his author.

Sincerely, Your Reader (ReaderGod, to you).

Anger is only one of the potential reactions we could have to Gaarder’s thrilling novel. For those readers who do not want to be disturbed, this story of a 14-year-old girl in a comfortable Norwegian suburb who embarks on a philosophy course with a mysterious stranger should be put down approximately midway. At this point, they will have received a crash course in the Greats: from the Norse myths to Thales, to Democritus, Socrates, Plato, Aristotle, Descartes, Spinoza, Locke, Hume, Berkeley, Kant, Hegel, Kierkegaard, Marx, Darwin and Freud.

Their guide, Alberto Knox, and his sometimes Socratic, sometimes feisty pupil, Sophie, are distracted from their pursuits only by a disturbing series of missives to another little girl named Hilde (almost exactly Sophie’s age) from her father, Albert Knag, a major in the U.N. Battalion in Lebanon (Sophie’s father is the captain of an oil tanker and is also away a lot). These appear in Sophie’s mailbox, in Alberto’s mailbox, in schoolbooks, on woodland paths, and on the insides of banana peels. In most, the message is the same: Happy 15th Birthday. I’ll be home to celebrate!

As both Sophie’s and Hilde’s birthdays approach, this visit becomes increasingly ominous. Why? Because Alberto and Sophie suspect that they are mere characters in a book written by Major Knag for his daughter Hilde back in Lillesand, Norway. In fact, their landscape is increasingly peopled with characters from other books, and Alberto sets out (just as the course takes up the Romantics) to create a rebellious plan to escape authorial dictatorship before the book is finished and they dissolve into the fictional universe.

As a reader, you don’t want them to stay in Fictionville because you have come to care about them, particularly Sophie, with her sweet but out-of-it mother, her love of animals and her attachment to her absent father.

As you can imagine, there’s a lot of “Through the Looking Glass” in the parallel lives of Sophie and Hilde, mirrored in the reader’s own discomfort about who is actually pulling the strings in this puppet show. It’s intriguing and disturbing to mistrust your author, to wonder what is real within the fictional universe, to wonder nervously who is watching you while you read, and ultimately whether you are a character in someone else’s book. If, in fact, you are (and I cannot say for sure) you should hope that the writer is as generous and talented as Jostein Gaarder.

Here’s another letter an author like Mr. Gaarder might get from a reader:

Dear Mr. Gaarder:

Thanks for suggesting so many good books to read, for making me think about the act of reading and for reminding me how much I miss my dad. Sincerely, Your Reader.