I think it best that I begin with the end. On March 1, I and dozens of Dan’s friends and fellow activists received a two-page notice that he had been diagnosed with incurable pancreatic cancer and was refusing chemotherapy because the prognosis, even with chemo, was dire. He will be ninety-two in April.

Last November, over a Thanksgiving holiday spent with family in Berkeley, I drove a few miles to visit Dan at the home in neighboring Kensington he has shared for decades with his wife Patricia. My intent was to yack with him for a few hours about our mutual obsession, Vietnam. More than fifty years later, he was still pondering the war as a whole, and I was still trying to understand the My Lai massacre. I arrived at 10 a.m. and we spoke without a break — no water, no coffee, no cookies — until my wife came to fetch me, and to say hello and visit with Dan and Patricia. She left, and I stayed a few more minutes with Dan, who wanted to show me his library of documents that could have gotten him a long prison term. Sometime around 6 p.m. — it was getting dark — Dan walked me to my car, and we continued to chat about the war and what he knew — oh, the things he knew — until I said I had to go and started the car. He then said, as he always did, “You know I love you, Sy.”

So this is a story about a tutelage that began in the summer of 1972, when Dan and I first connected. I have no memory of who called whom, but I was then at the New York Times and Dan had some inside information on White House horrors he wanted me to chase down — stuff that had not been in the Pentagon Papers.

I was planning to write about my friendship with Dan after he passed away but last weekend my youngest son reminded me that he still had some of the magic trick materials that Dan had delighted him with in the mid-1980s, when Dan was crashing with our family, as he often did when visiting Washington. “Why not write about him now?” he asked. Why not?

I first learned of Dan’s importance in the summer of 1971, when he was outed for delivering the Pentagon Papers to the New York Times a few weeks after the newspaper began a series of shattering stories about the disconnect between what we were told and what really had been going on. Those papers remain today the most vital discussion of a war from the inside. Even after the New York Times exposures, their seven thousand pages would be rarely read in full.

I was then working for the New Yorker on a Vietnam project and had learned that it was Dan who did the leaking a week or so before his name became public. His outing was inevitable, and on June 26, after hiding out in Cambridge, Dan strolled to the US Attorney’s office in Boston — there were scores of journalists waiting — and had a brief chat with the reporters before turning himself in for what all expected would be the trial of the decade. He told the crowd that he hoped that “the truth will free us of this war.” And then, as he fought his way to the courthouse steps, a reporter asked him how he felt about going to prison. His response struck me then and still makes me tingle: “Wouldn’t you go to prison to help end this war?”

I had done my bit in exposing the My Lai massacre and publishing a book about it in 1970. I was then in the process of writing a second book on the Army’s cover-up of the slaughter. “Hell, no,” I thought to myself, “No way I would go to jail — especially for telling an unwanted truth.” I followed Ellsberg’s subsequent trial in a Los Angeles federal court and even wrote about the wrongdoing of the White House creeps who broke into the office of Ellsberg’s psychoanalyst — at the request of President Richard Nixon. (The government’s case was thrown out after the extent of the White House–ordered spying on Ellsberg became public.)

It was early in the election year summer of 1972 when Ellsberg and I got in touch with each other. I was banging away on the losing Vietnam War and CIA misdeeds for the Times. Nixon looked like a sure thing, despite continuing the hated war, because of stumble after stumble for the campaign of the Democratic nominee, Senator George McGovern. Dan had two stories that he thought could change the dynamics of the November election.

I liked him right off the bat. He was so earnest, so bright, as handsome as a movie star, and so full of the kind of inside information about the Vietnam War that few others had. And so willing to share them with no worry about the consequences. He understood that as the source of highly secret information and procedures he was taking all the risks and that as a reporter I was going to write stories that would get acclaim and put me at no risk.

At some point in our chats, I brought him home for a good meal. His campaign against the Vietnam War was literally consuming him, and he immediately engaged with my wife and our two small children. He did magic tricks, he was marvelous on the piano — Dan could play the Beatles and Beethoven — and he connected with all of us. Our friendship was locked in — forever. I confess that late at night — we were both night owls — he and I would walk the dog and find time to sit on a curb somewhere and smoke a few Thai sticks. How Dan always managed to have a supply of these joints from Southeast Asia I chose not to ask. He would talk about all the sealed and locked secret files of the Vietnam War that he could recall, with his photographic memory, in near perfect detail.

In the early 1980s, I was writing a long and very critical book about Henry Kissinger’s sordid days as Nixon’s national security adviser and secretary of state, with a focus on Vietnam. At one point, Dan spent more than a week in our home, rising at 6 a.m. to read the twenty-three hundred pages of typed manuscript. He understood that I did not want his analyses or disagreements with my conclusions, but only factual errors. One morning Dan told me I had misread a mid-1960s Washington Post piece on the war by Joe Kraft, whose column was then a must-read. I argued, and he was adamant. So I drove downtown to my office, dug through boxes of files and found the column. Dan had remembered the details of a two-decade-old column in a daily newspaper. His memory was scary.

There were two White House abuses he wanted me to expose before the presidential election in the fall of 1972. Dan told me that Nixon and Kissinger — for whom Dan had written an important early policy paper after he was appointed national security adviser — had been wiretapping aides and cabinet members. The second tip Dan had for me was that Kissinger had ordered some of his aides to produce a plan for using tactical nuclear weapons in South Vietnam, in case they were needed to end the war on American terms. If I could get one or two sources — by this time there were a number of former Kissinger aides who had quietly resigned over the Vietnam War — on the record, Dan said, it just might get the Democrats into office. It was the longest of long shots, but I tried like hell all summer to find someone who had firsthand information, as Dan did not, and who was willing to confirm Dan’s information, even if on background. Of course, it was understood I would have to tell Abe Rosenthal, executive editor of the Times, who my off-the-record source was.

It was a lousy summer for me, because there were a few former Kissinger aides who easily confirmed Dan’s information, but would not agree to my providing their names to the Times. In one case, with a very decent guy who very much hoped he would get a senior job in a future administration, I came close, aided by the fact that his wife — I always conducted such visits at night — said to her husband, “Oh, for God’s sakes just tell him the truth.” She said it over and over. Talk about a painful experience. Needless to say, their marriage did not last long. The wife’s anger that the truth was not being told helped me understand Dan’s obsession with a war whose worst elements were simply not known to the public. I wasn’t able to get any source on the record in time for the election, but in subsequent years I did get the stories.

There was one story Dan told me in late 1993 that seemed to capture the secret life on the inside of a major war. He had gone back and forth on short missions to South Vietnam while working as a senior State Department official, but he jumped at a chance in mid-1965 to join a team in Saigon committed to pacification — winning hearts and minds — of the villagers in the South. Its leader was Ed Lansdale, a CIA hero of counterinsurgency for his earlier efforts in routing communist insurgents in the Philippines.

I always took good notes in my meetings with Dan, not because I planned to write about him at some point — I knew he would write his own memoirs — but because I was getting a seminar on how things really worked on the inside. Read his words, and you can judge for yourself how complicated life could be at the top.

“In 1965,” Dan began, “I had done a study of the Cuban missile crisis and I had four operational clearances above top secret, including U-2 clearances” and National Security Agency clearances. He had also interviewed Bobby Kennedy two times about his role in the crisis. Ellsberg’s clearances were so sacrosanct that he was supposed to register in a special office upon arrival in Saigon and from then on he would not be allowed to travel outside of Saigon without an armored car or in a two-engine airplane or better. He got around the system by not deigning to register, a rarity in a world of war where top secret clearances were seen by many as evidence of machismo.

And so Ellsberg went off to work in Saigon with Lansdale. “For one and one half years,” Ellsberg said, “I spent nearly every evening listening to Lansdale talk about his covert operations in the Philippines and earlier in North Vietnam in the 1950s. By this time I’d been working with secrets for years and thought I knew what kind of secrets could be kept from whom. I also thought Ed and I had a good working knowledge of each other and our secrets. Every piece of information was cataloged in your mind and you knew to whom you could say and what you could say. In all of this, Jack Kennedy was mentioned and so was Bobby, but there was no mention by Lansdale of Cuba and no mention that Lansdale had ever worked for Jack and Bobby Kennedy.”

A decade later, after both Kennedy brothers had been assassinated, I wrote a series for the New York Times on the CIA’s spying on hundreds of thousands of American anti-Vietnam war protesters, members of Congress and reporters — all in direct violation of the agency’s 1947 charter barring any domestic activity. It led to the establishment of the Senate’s Church Committee in 1975. It was the most extensive congressional inquiry into the activities of the CIA since the agency’s beginning. The committee exposed the assassination activities of the CIA, operations undertaken on orders that clearly came from Jack and Bobby Kennedy, although no direct link was published in the committee’s final report. But the committee reported extensively on a secret group authorized by Jack Kennedy and run by his brother Bobby to come up with options to terrorize Cuba and assassinate Fidel Castro. The covert operation had the code name Mongoose. And it was led, the committee reported, in 1961 and 1962 by Lansdale.

Ellsberg told me he was flabbergasted. “When I heard about Lansdale and Mongoose,” he said, “it revealed to me an ability to keep secrets on an insider level that went far beyond what I had imagined. It was like discovering your next-door neighbor and your weekend fishing companion” — Ellsberg, it should be noted, never went fishing in his life — “and close, dear friend who, when he died, turned out to have been the secretary of state.

“It was astounding, because Mongoose was exactly the kind of operation I’d expected to hear about from Lansdale. He told about covert operations all the time. I think Ed had been told by President Kennedy to ‘keep his fucking mouth shut.’

“When you’ve been in a system with as high a level as possible of secrecy, you understand that things do get talked about. And you get a sense of what is usually held back. I was hearing all about other covert operations, but somebody — not Lansdale — had put a lid on Mongoose.”

After the assassination of Jack Kennedy, Ellsberg theorized, “any far reaching investigation into his death would have to lead to many covert operations.” His point was that there was no evidence that the Warren Commission set up to investigate the assassination had done so.

In all of Dan’s many hours of tutoring, as I understood years later, he understood and empathized with my eagerness — even my need — to learn all that I could about his world of secrets and lies, things said out loud and hidden in top-secret documents. And so he happily became my tutor and taught me where and how to look inside the recessed corners of the American intelligence community.

In return, I gave him my friendship and welcomed him into my family. He loved long talks with my wife, a doctor, teaching the kids magic tricks, and playing Billy Joel songs and similar stuff on the piano for them. We all sensed early on that there was a need for him to be an innocent kid, too, if only to serve as a brief respite from his constant anxiety and the guilt he carried in his soul about what his America had done to the Vietnamese people.

Dan was showing me an insider’s love, just as he and Patricia radiated love and acceptance to all their many friends and admirers who, like me, will never forget the lessons he taught us and what we learned.

No way I’m going to wait for him to move along without saying what I want to say right now.