Fact Flirts With Fiction in `The Da Vinci Code'

What's the secret to "The Da Vinci Code," the novel by Dan Brown that's been smiling down from fiction best-seller lists since it debuted in April? No, it's not the inside joke behind the Mona Lisa's languid smile, or the redhead seated on the right hand of Jesus in the "Last Supper." It's the note Brown tacks onto the first of his 454 printed pages (Doubleday, $24.95) under the cut-and-dried title "Fact."

"All descriptions," Brown writes, "of artwork, architecture, documents, and secret rituals in this novel are accurate."

OK, so what does all this cloak-and-dagger detail mean? Is the Christian church based on a lie? Does a secret society, once led by Leonardo da Vinci, protect the truth? Are tourists tramping all over it right now?

If these are among your questions, you've probably read the book, a real page-turner about Harvard University "symbologist" Robert Langdon and his hair-raising encounter with the Holy Grail. It's hovered near the top of the New York Times best-seller list for 15 weeks. Columbia Pictures has bought the movie rights, with the hope that some actor will do for symbology what Harrison Ford did for archaeology.

But back to the question at hand. What does all this "accurate" description add up to? How much of "The Da Vinci Code" is true and how much is a good story? And what difference does it make?

"It touches on enough strands of popular speculation and mythology that readers will think of it as more factual than it is," says Charles Lippy, a history of religion professor and an expert on popular culture who says he enjoyed the book but never forgot it was a novel. Other readers may be more gullible.

Combine that, Brown's authoritative tone and some readers' penchant for conspiracy theories, and it may be that "The Da Vinci Code" could use a little cracking. Without giving too much away, here's a quick reader's guide to some key concepts.