Criticism of The Da Vinci Code "Smithy Code Jackie Fisher who are you Dreadnought", referring to the British admiral whom Judge Smith admires. As with the book, this secret message made use of Fibonacci numbers for its encoding. Dan Brown has been sued twice in The United States by author Jack Dunn who claims Dan Brown copied his book The Vatican Boys (1997) to create The Da Vinci Code, Angels & Demons and Brown's now famous character Robert Langdon. Jack Dunn calls Dan Brown's actions, "The Largest Literary and Movie Crime in History." At a conference on April 28, 2006 Archbishop Angelo Amato, the secretary of
The Da Vinci Code Geoffrey Pullum and others posted several entries critical of Dan Brown's writing, at Language Log, calling Brown one of the "worst prose stylists in the history of literature" and saying Brown's "writing is not just bad; it is staggeringly, clumsily, thoughtlessly, almost ingeniously bad". Roger Ebert described it as a "potboiler written with little grace and style", although he said it did "supply an intriguing plot". In his review of the film "National Treasure", whose plot also involves ancient conspiracies and treasure hunts, he wrote: "I should read a potboiler like "The Da Vinci Code" every once in a while,