NATCHEZ &045; Ask Greg Iles what his new book is about, and he finds it hard to boil the theme down to a few sentences.

But that’s understandable, considering he is writing about philosophical ideas he has been considering for most of his life.

&uot;This is the hardest book I’ve ever had to talk about,&uot; Iles said. &uot;It started with big ideas rather than the story or the characters.&uot;

Since he was younger, Iles said he has been &uot;obsessed with the basic questions of the universe.&uot;

&uot;I knew the day would come when I would incorporate those themes in to a novel,&uot; he said. &uot;In a way, this book’s written very differently than my other books.&uot;

&uot;The Footprints of God&uot; uses the framework of a thriller to explore the intersection of religious and scientific theories about the origin of the universe.

&uot;I don’t think in the end science and religion are far apart,&uot; Iles said.

Iles’ protagonist is an ethicist assigned to a secret government project to build a supercomputer that rivals the human brain.

&uot;It’s about a computer that works like the human brain,&uot; Iles said. &uot;Even though we don’t understand how the brain works, this computer puts us in range of something as powerful as the human brain.&uot;

As Dr. David Tennant becomes more involved with the project, he also becomes more wary of its ambitions. His anxiety is coupled with hallucinations that lead him to consult a psychologist &045; one who goes with him when Tennant’s suspicions come to a head and the government gives chase.

For Iles, combining his &uot;big ideas&uot; with a plot that would keep readers interested was a challenge.

He did it, he said, by &uot;breaking all the rules of a thriller.&uot;

Iles said Tennant’s character is not unlike himself, a man who has considered theories about the origin of God and the universe for much of his life.

&uot;I like it, but it’s frustrating,&uot; he said of the process of boiling down his theories into a commercial novel. &uot;People could have trashed this book.&uot;

But reviews so far have been good. Publisher’s Weekly said &uot;Iles writes himself onto a high wire that stretches over a dangerous fictional chasm as Tennant begins to have narcoleptic seizures and see life through the eyes of Jesus Christ.

&uot;That this talented author makes it to the other side without falling is testament to his ingenuity and intelligence,&uot; the reviewer wrote.

&uot;Most people aren’t allowed to do this,&uot; Iles said of the novel.

And he admits to some intense discussions with his publisher about the direction the novel would take.

&uot;I’m taking the most cutting-edge science and the most ancient and modern religious theories, and I’ve tied it up as a thriller,&uot; he said.

At its heart, the novel is a chase story, Iles said.

&uot;Like all my books, it’s about good and evil,&uot; he said. &uot;And why do good people end up doing bad things.

&uot;It offers some theories about the origin of the universe and what God is.&uot;

And Publisher’s Weekly, at least, believes the book will appeal to readers who enjoy both a thriller and a book about larger themes.

&uot;Readers interested in the exploration of religious themes without the usual New Age blather or window-dressed dogma will snap up this novel of cutting-edge science,&uot; the review says.

Iles’ writing schedule does not allow a lot of time to publicize the book, but he does have some upcoming appearances &045; both local and national. On Saturday, he signed books at a benefit for Trinity Episcopal Day School, as is his tradition.

On Aug. 19, Iles will appear on NBC’s &uot;Today&uot; show. He will also participate in a day-long series of radio satellite interviews and a book conference called &uot;Poison Pen&uot; in Scottsdale, Ariz.

But for the most part, Iles is trying to work on his next book. Producing one novel per year, he has a tight schedule.

Iles even admits the novel might fall short of his own expectations as an artist. But he doesn’t think that’s necessarily a bad thing.

&uot;If I’d had another year, people would have liked it less,&uot; he said. &uot;It would have been this grand treatise.&uot;

Still, Iles &045; who has authored eight best-selling novels &045; said he looks for success from &uot;The Footprints of God.&uot;

&uot;I have a feeling about this book,&uot; he said. &uot;The critical mass is coming.&uot;