An example: For the Nixon book, I interviewed a lawyer and literary agent named Arthur Klebanoff, whom I had first met as a young assistant to Daniel Patrick Moynihan in 1970. After we had finished talking about how the Nixon Domestic Council worked, Art said: “You know I was Bob Haldeman’s agent when he wrote The Haldeman Diaries .” He then told me that sections excised for security and privacy in the book (and a CD with additional material) were listed as “Secret” but had never actually been classified by the government. After practically running to the National Archives, I discovered it was true and that no one had even looked at those pages. Suddenly I was reading about Haldeman’s role as a buffer between Nixon and Kissinger, each of them telling him the other one was nuts. Actually it was Kissinger who seemed the hysterical one, telling the President the Russians were about to invade China or land in Cuba: “If you do nothing, they will call you a weakling, Mr. President.” The line usually worked, but the invasions seemed unlikely to Nixon. So unlikely, thought Nixon, that he told Haldeman not to let Kissinger back into the Oval Office until he’d seen a psychiatrist.

I love it. But it takes years. It is something like what I imagine diamond mining to be. You move around the muck and mire for weeks, for months, for years, and then suddenly something sparkles, and you look at it. The found gems I remember best were documents from early 1961 indicating that President Kennedy knew in advance that the Berlin Wall was going up—and that he wanted it up. He sent repeated signals to the Soviets, publicly and privately (some through a KGB courier named Georgi Bolshakov, whom I tracked down in Moscow) that what they did on their side of the border was their business, as long as they did not interfere with the inspection rights of the Allied occupiers of West Berlin—the United States, Great Britain, and France. We had and retained the right to send officers into East Berlin on observation missions—Checkpoint Charlie and all that.

What Kennedy had figured out was that sooner or later the communists were going to have to take military action to stem the flow of people fleeing from east to west through Berlin. Two thousand a day were walking in, driving in, taking the subway. They were the young, the best and the brightest, engineers, doctors, nurses, looking for new lives. That was Khrushchev’s problem. Kennedy’s problem was that there were only 15,000 Allied soldiers in Berlin, surrounded by hundreds of thousands of Red Army troops. To “save” Berlin or defend West Germany or even all of Europe, Kennedy would have to use nuclear weapons, and he did not intend to do that.

“Better a wall than a war,” he said in private. In public of course he condemned the wall. He would have been impeached if the truth had been known. But I believe the wall probably prevented a third world war. If there had been another great war in those days, it would not have started in Cuba or Africa; it would have started in Europe, in Berlin. That story was a secret—and a valuable historical lesson—that could be revealed only in archives. That is the point of archives. The truth, or the facts, shall make us free.

I set out years ago thinking that presidential history was not as tidy as what I had read about it in my life. Working in the White House, I had learned that everything happens at once, that a writer had to consider it all: what was on the President’s mind and his desk on a particular day. What he knew and when he knew it. Kennedy didn’t make decisions knowing he would be assassinated. Nixon didn’t know he would have to resign. It has been said that history is lived forward and written backward. With open archives it is possible to write history forward by focusing tightly on what the President knew that day, that hour, that minute—not on hindsight, not on what we would all find out years later.

So I need those papers. They mean money to me too; this is how I make my living. I do battle for them. President Bush is on the other side of this game. So is Alexander Haig, a major figure in the book I am now doing on the Presidency of Ronald Reagan. Here is the letter I got recently (March 1, 2002) from the assistant chief of the Manuscript Division of the Library of Congress, where Haig “donated” his papers.

Dear Mr. Reeves:

We have been notified that your request for permission to consult Alexander Haig Papers has been denied. Please let me know if we can be of any further assistance.

I guess I’m on my own. But that’s the way it often is with politicians, government, and history. There is an “us” and “them” quality to the game, and I am greatly influenced by what I call Kelly’s Law. I learned it in 1984 on a road in Honduras near Soto Canto, the principal U.S. base in the covert war against the Sandinista government of Nicaragua. I ran into a roadblock and stepped out of the car, standing next to an American trucker carrying a huge load of telephone poles on a U.S. Army truck, who had also been stopped. “Sgt. Kelly” was the name on his uniform tag. Four old C-47s swept over the range of hills in front of us, coming our way. Paratroopers began jumping out of them.

“What’s that?” I said.

“What’s what?” Sergeant Kelly answered.