Lounging on the floor of his hotel room, with his tie askew, hair tousled, and back propped against the bed, Seymour Hersh doesn't seem to match the crisp, tailored figure gazing out from the jacket photo of what is bound to be the summer's most talked-about book.
But even investigative journalists have to relax, especially at the end of a grueling week of interviews about a book that aroused a storm of controversy even before being published June 13.
''The Price of Power: Kissinger in the Nixon White House'' (Summit Books, 698 pp., $19.95) presents the first detailed examination by an outsider of the conduct of foreign policy during Mr. Nixon's first administration (1969-73).
It is a jolting account, not just because it penetrates deep inside the hidden processes of policymaking, but because it presents a devastating portrait of former National Security Adviser Henry Kissinger, later secretary of state. We see him here as a man obsessed by a single objective - power at almost any cost.
The book has made news because:
* It alleges Mr. Kissinger gained access to President Nixon's inner circle by providing secret knowledge of the Paris peace talks on Vietnam, gained as a trusted associate of Lyndon Johnson.
* It also charges that, while courting the Republican camp, Kissinger also offered Nelson Rockefeller's private files on Nixon to aides of Democratic contender Hubert Humphrey.
* It details the administration's alleged roles in the overthrow of Cambodia's Prince Norodom Sihanouk and Chile's President Salvador Allende Gossens.
* It reveals links between SALT negotiations and the 1972 US wheat sale to the Soviet Union.
* It charges that Nixon undercut Kissinger's nearly certain peace initiative with the North Vietnamese in the autumn of 1972 because pollsters told the President a settlement before the election could narrow his margin of victory.
* It produces the first evidence of a rumored contribution from the Greek military junta to the Nixon campaign coffers.
And much more.
(Kissinger hasn't commented on the book in full, but he immediately branded the charges of double-dealing in the '68 presidential campaign as a ''slimy lie.'' Later he amplified by saying he had only answered a few questions from the Nixon camp about the probability of a bombing halt and had ''no recollection'' of offering any file on Nixon to the Humphrey camp.)
''The Price of Power'' has already been criticized by some as a ''hatchet job'' and an effort to ''get Henry.'' But others have praised Hersh for producing an exhaustive treatment of a difficult subject, and managing to sound like a historian instead of a muckraker.
Hardly anyone has had time so far to ponder all 460,000 words carefully. Undoubtedly, months or years of analysis will be needed before a final verdict can be reached.
In a Monitor interview at his hotel, Hersh is quick to explain that writing a book on Kissinger wasn't a personal obsession, as at least one critic has charged. He says the idea came from his editor, Jim Silberman, first in 1977, then again in '79: ''It wasn't something I was lying in wait to do.''
Hersh says he didn't know Kissinger well before starting his research. But the reporter who uncovered the My Lai massacre frankly admits he approached the subject with bias: ''I thought his Vietnam policies had been immoral and unprincipled.''
Hersh regarded this conclusion as more troubling than the fact that Kissinger was a ''hawk.'' In covering the Pentagon for the Associated Press during the early part of the war, Hersh says he developed great respect for some hawks who were straightforward, honest, and committed to their positions. But ''I never recognized Kissinger as one whose primary motivation was principle.'' If Hersh were producing a play on the Nixon era, he would cast Rod Steiger in the Kissinger role, he says, and would style the lines on Shakespeare's Iago - ''Kissinger was a schemer, sad to say.''
The author insists, however, that his preconceptions about the one-time Harvard professor and Rockefeller adviser are beside the point. ''I'm a professional reporter; I'm judged by what I write. I'm willing to be judged by my book.''
He maintains that outspoken critics so far haven't attempted to deal with ''a single fact in the book.'' Newsweek intimated that some recent slams against Hersh in newspapers and on television may have been orchestrated by the Kissinger camp, ''calling in chits from friends in the press for Kennedy-style damage limitation.''
Hersh has said that Kissinger's most enduring diplomacy was with the press. When ''Sy,'' as he is known to friends and colleagues, joined the New York Times in 1972, he recalls that ''there were a few people who were very proud they had a private phone number for Henry Kissinger. They could call and get an answer to anything in 15 minutes, at any time. That was a badge of honor.'' Hersh says Kissinger still has tremendous loyalty, because ''he's still an incredible source.''
For the kind of substantial criticism Hersh hopes to see, he realizes he'll ''have to wait for more reasoned judgment. . . . It all boils down to Kissinger's version of the truth or mine. I'm going to stick with mine and pray that critics questioning it will call up the people I asked and make their own effort to find out.''
In the four years he spent researching and writing this book, Hersh estimates he interviewed 1,000 people, some of them diplomats and former diplomats abroad, most of them one-time Kissinger colleagues or subordinates. ''People in the State Deparment and the CIA had a story to tell that no one had ever asked them about.''
When the first volume of Kissinger's memoirs was published late in '79, says Hersh, ''it enraged the diplomatic community, because nobody got any credit for anything. The book was a gold mine. If you read it closely in conjunction with everything else that had been said - and nobody did - you could see immense discrepancies, incredible contradictions between what he said and others had said. And whenever there was a dispute, it was always Kissinger who had fudged.''
Hersh began to see a pattern emerge, as the story came out about how Nixon, with Kissinger's help, consolidated control over foreign affairs in the White House, usually leaving Secretary of State William P. Rogers and defense chief Melvin Laird out in the cold. Hersh says diplomats were asked to report directly to the White House, ''backchannel'' (via CIA and National Security Agency facilities, where only clerks see the communications in transit and no records are kept).
Hersh says his best lead was a list of home addresses, as of July 19, 1969, for National Security Council members. He went right down the list and talked to everyone.
Asked whether the press could have been more thorough during Nixon's first term in uncovering the information Hersh got 10 years later, the author is ambivalent. He says reporters learned right away that Nixon and Kissinger were running the show and not letting others in government in on their planning. Nixon didn't talk much to the press, so as it turned out the only source of inside foreign policy information was the President's national security adviser. ''I wrote stories about Kissinger that today read like satire. We all did.
''But the ultimate subtheme of my book is: If the President of the United States chooses to lie to the American people, there's nothing we can do about it (immediately). He really has that power.''
Hersh describes the failures of the press to uncover the secret policies of the first Nixon administration as ''enormous'' - 14 months of secret bombing in Cambodia, wiretaps against staff and reporters, activities against Daniel Ellsberg and Chilean President Allende.
''When you add up what we didn't do, the notion that somehow we won a victory in Watergate becomes sort of hollow,'' he says. ''In fact, you can argue that we helped make Watergate possible. If a president can secretly throw 110,000 tons of bombs on a country (Cambodia), why can't he break into the Watergate? Who's going to stop him?''
Where does Hersh set the ''price of power'' alluded to in his title? The ''human cost'' was tremendous, he says, because the Vietnam war could have been ended sooner than it was. Sources in Vietnam told him that, though the North wasn't willing to settle for a negotiated peace in '69, it would have in '71 or '72.
Hersh also feels the cost can be measured in a profound loss of respect for America among countries of the third world. ''The Nixon administration was interested in superpower politics, was contemptuous of the third world, and it showed. One of the messages of the book is that we still don't know the bottom line'' of the costs.
After talking for an hour, Hersh is eager to spend a quiet evening. In the morning he'll head home to his wife and three children in Washington - where, according to reports, no one is allowed to mention the name Kissinger at the dinner table.