Long ago, back in Sunday school in Nebraska, something happened that changed how television talk legend Dick Cavett would think about faith forever.

When he was a boy, his mother got breast cancer. Then a "seemingly helpful old lady said, 'Dickey, if you pray your mother will get well,' and," he said with a long pause, "she didn't."

This anecdote was highly relevant, during a recent New York City forum, because Cavett was interviewing author Eric Metaxas about his new book, "Miracles: What They Are, Why They Happen, and How They Can Change Your Life."

In other words, young Cavett prayed for a miracle, it didn't happen and that certainly did shape his life.

"That didn't help either my attitude toward religion or helpful old ladies," he said, drawing sad laughter from the live audience during this "Socrates In The City" webcast. "I felt that I did it wrong, of course. I didn't do it right and I was partly responsible."

Metaxas, founder of the "Socrates" series, added: "Is this old lady still alive? Because I would like to give her a piece of my mind."

Cavett, of course, knew he was playing devil's advocate. This was the role an Upper West Side audience would have expected him to play in a chat that included -- in addition to the Big Bang and the Resurrection -- references to Woody Allen, Carl Sagan, Barbra Streisand, Jerry Falwell, Groucho Marx, Christopher Hitchens, Bill Buckner and, as a running punch line, former Vice President Dick Cheney. 

One of the problems with "miracle" discussions is that there is no one definition, noted Metaxas, in the book. In a dictionary a miracle is "an extraordinary event manifesting divine intervention in human affairs." The Christian scholar C.S. Lewis -- author of a 1947 bestseller on the topic -- argued that miracles were unique events that break patterns so well established that few people even think they can be broken.

Skeptic David Hume set the standard for public debate, defining "miracle" as a "transgression of a law of nature by a particular volition of the Deity, or by the interposition of some invisible agent."

But when religious believers use the term -- Metaxas collected stories from dozens -- they often talk about two other kinds of miracles.

The first is when something unusual definitely happens, but it may or may not be a miracle. For example, why do some cancers go into remission? This may be natural, but doctors don't really know.

Also, many of the stories Metaxas heard center on personal revelations -- such as prophetic dreams -- that don't violate natural laws, but are certainly strange. Then there are events that may not violate natural laws, but the odds against them are so high that it's almost irrational to think they are random.

For skeptics on the outside, stressed Cavett, the big questions have to do with why miracles happen in some cases, but not others. And why does God -- like an "auctioneer" -- need to hear prayers in the first place and, if so, does God have a "minimum number that he needs to get" before the miracle formula works?

These are not skeptical questions, stressed Metaxas. They are rational questions.

"At some point there are no answers to this," he said. "Who knows? These are mysteries. When I pray, I don't know whether if I prayed five minutes longer it will have an effect. But I do think that the mind wants to ask those questions."

But there is "no trick" that controls the "God of results," he said. It would be a form of "dead religion" to think believers can say the right number of Rosary Prayers and then the "magic will happen. ... No, I think something else is going on."

When considering miracle stories, either historic or contemporary, Metaxas said he hopes both believers and skeptics will ask tough questions and weigh the evidence, even if this challenges their presuppositions.

"There are mysteries here and I think that it is a bit arrogant for us to simply dismiss them or to claim that we fully understand what is happening," he said, in a telephone interview.

"But there is no reason that we can't talk about these things, even on the upper West Side of Manhattan. There is nothing to fear, here. We are talking about the nature of reality -- period."