Brown says he used historians' ideas, among others, for Da Vinci Code

Dan Brown's book 'The Da Vinci Code' has sold millions of copies around the world.

LONDON - Author Dan Brown today conceded that some of the ideas he took from two historians who accuse him of plagiarism were essential to "The Da Vinci Code," but said the bestseller had many other important themes too.

On his third and final day in the witness box, the 41-year-old expressed frustration during a grueling session of cross-examination in the closely-watched copyright case at London's High Court.

Michael Baigent and Richard Leigh wrote a 1982 book of historical conjecture called "The Holy Blood and the Holy Grail," which they claim Brown lifted wholesale for his novel.

They are suing Brown's British publisher, Random House, which also happens to be their own.

The books share the idea that Jesus married and had a child by Mary Magdalene and that their bloodline was protected by the mysterious Priory of Sion.

"They are among the many, many ideas that are essential to The Da Vinci Code," Brown replied, when asked by the claimants' lawyer whether the ideas in Holy Blood provided the "backbone" to his novel.

The religious thriller has made Brown one of the most successful authors of all time, selling about 40 million copies.

Random House argues that neither Brown nor his wife Blythe had read the 1982 Holy Blood book by the time he composed the synopsis for The Da Vinci Code in January, 2001.

Justice Peter Smith sought to clarify the point, asking the claimants' lawyer, Jonathan Rayner James: "Do you accept Mr. Brown's evidence as to when he said he first saw Holy Blood, Holy Grail?"

Rayner James replied: "Mr. Brown denies it. We say his wife had it by that time."

Blythe, who has not been in court, played a big part in the creation of The Da Vinci Code, typing up research, searching the internet and proposing ideas which appear in the finished novel.

Rayner James wondered how Brown could know the origin of his ideas when so much research had been carried out by Blythe.

"You are, in fact, placing total reliance on her and her research," he said, referring to one of several documents she compiled for Brown during the creation of the novel.

He also asked Brown to say what he thought the word "plagiarism" meant.

"In the absolute simplest terms, I understand plagiarism to be taking someone else's work and passing it off as your own," he replied.

When pressed on whether the concept had a wider meaning than purely infringing someone's copyright, he said:

"I'm not a lawyer. I don't understand the intricacies of copyright infringement," before adding that he believed plagiarism also had "a moral implication."

Brown's cross-examination has been dominated by detailed questions about punctuation, spelling, and to what extent the language and ideas of The Da Vinci Code mirror those of the Holy Blood.

For example, several minutes were spent establishing whether the word "saviour" was spelled in the English or US style, without the "u," when it appeared in an unfinished version of the novel from July, 2002.

At times showing signs of impatience, Brown sighed, shook his head and joked that his eyesight had deteriorated during the case as a result of the minutiae he had been forced to study.

Hearings are due to resume on Friday, and the case is scheduled to end on Monday. The judgment could take weeks.

- REUTERS