Dan Brown spent much of his second day on the witness stand flipping through thick books of documents as "The Da Vinci Code" author continued his defense Tuesday against allegations that he ripped off the ideas for his megaselling novel.

In a small, crowded London courtroom, Knights Templar and Freemasons were out and footnotes and computer programs were in, with Brown questioned about everything from his wife's penmanship to the word processing program he uses.

Lawyers for writers Michael Baigent and Richard Leigh — who are suing Random House, Brown's publishers, for copyright infringement — picked their way through the research methods used by the author and his wife, Blythe Brown. They were trying to determine when the Browns first read their book "Holy Blood, Holy Grail."

Baigent and Leigh, whose book also was published by Random House, say Brown's historical thriller "appropriated the architecture" of their 1982 nonfiction work; the American author says that assertion is "completely fanciful."

Under questioning by the plaintiffs' lawyer, Jonathan Rayner James, Brown testified that he was certain the couple only read "Holy Blood, Holy Grail" after he had submitted to his agent, in January 2001, his synopsis for the novel that would become "The Da Vinci Code."

"I think it would be very unlikely that Blythe would be reading it without my knowledge," Brown said. "I'm very doubtful that she would buy it and I wouldn't know."

Brown has acknowledged they read "Holy Blood, Holy Grail," while researching "The Da Vinci Code," but said they also used 38 other books and hundreds of documents and that the British authors' book was not crucial to their work.

While some of Brown's characters from "The Da Vinci Code" — which has sold more than 40 million copies since it was released in March 2003 — were mentioned in the courtroom, the person most frequently spoken about was Blythe Brown, who was not present.

Brown has testified that he's a very private person. So, too, is his wife, who won't be taking the stand in the case.

"My wife and I are very close. I firmly believe I can answer any questions regarding her assistance to me in the research of my book," Brown said in his witness statement. "She dislikes the public attention and I [see] no reason why she should be put through the stress that the glare of publicity would cause.

"The coverage of this case has been widespread. I have been thoroughly jostled by the press, and my wife would have hated it."

Brown is expected to testify again on Wednesday.

If Baigent and Leigh succeed in securing an injunction to bar the use of their material, they could hold up the scheduled May 19 film release of "The Da Vinci Code," starring Tom Hanks and Audrey Tatou.

Random House lawyers argue the ideas in dispute are so general they are not protected by copyright.

The third author of "Holy Blood, Holy Grail," Henry Lincoln, is not involved in the case. A lawyer for the plaintiffs, Paul Sutton, refused to say why he was not participating. Lincoln, who is in his 70s and reportedly in poor health, could not be reached for comment.