Here you have an incredibly ambitious, accomplished woman who comes up against some of the same problems that women in power come up against today. Cleopatra plays an oddly pivotal role in world history as well; in her lifetime, Alexandria is the center of the universe, Rome is still a backwater.

How does a woman in authority convey that authority? Is it possible for a woman to rule without sounding shrill? Is it possible for a woman to manage without manipulating? All of these things seem to me to be very much at the fore today, and were no less the case 2,000 years ago.

I checked to see if there'd been a really good book published in the last few decades. Then I started with what Cleopatra would have read, asking myself, 'What can we know about her education?' It turns out to be a very great deal, and bizarrely, no one had written about that before.

I don't think there is ever objective biography. Our vision of our subject is always shaped by who we are. So I do, of course, think the biographer's view is always something to keep in mind.

I once interviewed David Herbert Donald, the Lincoln historian, and we talked about how one deals with the secondary sources and the previous biographies. He said something which kept coming back to me as I worked on Cleopatra, which was: 'There's no further new material; there are only new questions.'

I went out to the desert where Cleopatra camped out with her mercenary army. It's a desolate outpost. Nothing has changed since her day. You realize how far she had to travel. Not only is it a good 150 miles against the current, you can't take a ship.

In an ideal world, the perfect biographical subject would have been the star of his penmanship class at grade school - and would thereafter write an English that positively sings.

Nonfiction writers are the packhorses of literature. We're meant to carry the story. If we can make it up and down the mountain by a reliable if not scenic route, we have delivered. Technique is optional.

Of course, women have long exercised influence behind the scenes. A few thousand years ago this drove Aristotle to distraction: 'What difference does it make whether women rule or the rulers are ruled by women? The result is the same.'

Reality does not easily give up meaning; it's the biographer's job to clobber it into submission. You're meant not only to tame it but to extract substance, to identify cause and axiomatic effect. You subsist on the tactical omissions, the hollow words, the oddly unconnected dots.

Recently a study proved that working from a larger, less cluttered computer screen increases concentration. I could have told them that. And yes, I write first drafts with a mechanical pencil and a yellow legal pad. There's good reason for this primitive behavior: I am a crackerjack typist. My hand moves far more quickly than my brain.

Strangely enough, politics may just be the one realm in which having kids imposes no penalty on women. Kids are practically a necessity. For scientists, or Supreme Court justices, or chief executives, or the woman who wants to learn to fly F-l8s off an aircraft carrier, it works differently.

The desk thing is a problem for me. The ideal one would be vast and perfectly clear. Yet the bane of the biographical existence is paper; if you're 'an artist under oath' you're writing from a mountain of documentation.

The interesting thing about Cleopatra is that she is such a shape-shifter. I mean through history we've all molded her to our times and our places. So there's room for a movie for her, but I don't think it will hew to the book.

We don't know how Cleopatra spent her days, but we do know how other Hellenistic monarchs spent their days. There has been a great amount of scholarship in the last 30 years about education in the Hellenistic world and women in the Hellenistic world. We now know how an upper-class woman was educated in her day.

We're talking about, essentially, the Roman historians, who wrote Cleopatra into the story mostly so that they could talk about the rise of Rome. And that is one of the problems, of course, in recounting her life. She's only ever apparent to us when there is a Roman in the room, or when her story intersects with the rise of Rome.

What we know about Cleopatra's looks is based purely on her coin portraits. Engraving was imperfect, and that when you are a ruler and you ask for a coin to be engraved with your likeness on it, you are probably trying to project a certain air of authority.

When finally I mustered the courage to tell a novelist friend that I was talking to editors about a biography, her reply was, 'Oh, that's okay. That's not a real book.'

Women enjoyed rights in Egypt they would not again enjoy for more than 2,000 years. They owned ships, ran vineyards, filed lawsuits, practiced medicine. Their husbands supported them after divorce. Their power was unprecedented.

You have to scuba dive in the Alexandrian harbor if you want to see what remains of the lighthouse of Cleopatra's day, and the water in the Alexandrian harbor is not really something you want to come into contact with.