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Dan Brown’s latest historical/conspiratorial/symbological mystery had a stellar first day, selling more than one million copies in the U.S., Canada, and the U.K. Amazon and Barnes & Noble reported that The Lost Symbol broke their records for first-day sales of an adult fiction book. “Adult,” in this case, being shorthand for “not Harry Potter.”

The e-book edition also posted big sales, and is currently the top seller for the Amazon Kindle.

Suzanne Herz of Knopf Doubleday says that this kind of fervent response was absolutely what the publisher expected. “There is no comparison,” she said, between The Lost Symbol‘s success and the early sales of Brown’s other novels. Anticipating massive demand, the publisher had to go back to press immediately prior to release in order to print an additional 600,000 copies (bringing the total number to 5.6 million).

According to Carolyn Brown, spokeswoman for Barnes & Noble, the book exploded past previous first-day records. “No other adult fiction title even comes close.” And what’s more, it may be spurring readers to buy other titles, too. “It is early, but so far we have seen a lift in sales of books about Freemasonry and secret societies, followed closely by those about early Christianity (Gnostic Gospels). We think interest in these genres will continue to be strong as the topics appeal to Brown’s core audience,” said Patricia Bostelman, vice president of marketing for Barnes & Noble, Inc. “As people read more from The Lost Symbol, we expect that the more esoteric titles and books about hermetics, noetics, quantum physics should start to gather momentum. And anything about the hidden mysteries and history of Washington are sure to see a pop as well.”

Brown’s sequel to his massively successful 2003 hit, The Da Vinci Code, a cultural symbol in its own right, finds his popular protagonist Robert Langdon back in the United States, returned from his two-book European vacation, and faced with another series of cryptic clues and shadowy goings-on. Fans are clearly excited at the prospect of another go-round with their favorite (likely by default) Harvard symbologist. Like one of Brown’s beloved ambigrams, whether read backwards or forwards, this spells major success for the author.