That's not conjecture, but Dan Brown's admission in court, according to this Telegraph article:
He spoke of his wife Blythe, his researcher, highlighting "exciting ideas, urging me to read the material myself and find ways to work the ideas" into The Da Vinci Code, which has sold 29 million copies.
"In particular she became passionate about the Church's suppression of women, and she lobbied hard to make it a primary theme of the novel."
Mr Brown added: "Somewhere during the research, and well before I started writing anything, I learned that Mary Magdalene was not in fact a prostitute, as I had been taught in Sunday school. This stunned me."
He said: "I am not sure I had ever seen Blythe as passionate about anything as she became for the historical figure of Mary Magdalene."
Of course, we should all keep in mind that this is "just a novel." After all, it's clear that Mr. and Mrs. Brown researched/wrote the novel in a spirit of fun and frivolity, right? Meanwhile, Brown also argued that he couldn't have relied too heavily upon Holy Blood, Holy Grail because it was over his head:
It also explained that it is his wife, Blythe, who came up with many of the ideas of the Da Vinci Code and passed them on to him as he carried out his research.
But when it came to the key issue of the case, the book The Holy Blood and the Holy Grail, he was keen to say that although it had been important for publicising ideas that appeared in his book, he himself hadn't got the ideas from it.
Indeed he said he hadn't even finished the book which he said was "hard to read".
But I thought his wife did most of the research? Was HBHG hard for her to read? One of them must have read it since ideas and phrases from that book appear numerous times in the novel.
Finally, in related news, I spoke yesterday for twenty minutes with an editor from the LA Times. And in an editorial in todays edition, the editors mention the work that Sandra Miesel and I have done showing Brown's reliance upon HBHG:
There certainly are similarities between passages of the two books. On his website, Carl Olson, coauthor of a book debunking the theories popularized by "The Da Vinci Code," cites more than a dozen instances in which Brown's words resemble or summarize parts of "Holy Blood, Holy Grail."
It might seem unfair for Brown to make a fortune from ideas generated by others' research. (He does give a nod to "Holy Blood, Holy Grail" in his book but says he didn't read it until after he'd written most of "The Da Vinci Code.") But writers have practiced such borrowing for centuries. Held to this standard, William Shakespeare, who took the plots for most of his plays from popular histories or even other fiction writers, would be condemned as a plagiarist.
As I told the editor I spoke with yesterday, my interest is not in Dan Brown being found guilty of plagiarism (although I'm certainly very interested in the case), but in readers appreciating that his ideas are not new, not unique to him, and are drawn from extremely dubious and shaky sources, that is, works of pseudo-history no real historian takes seriously. But, of course, we must all keep in mind that it's "just fiction," as Dan Brown explained in court in London...