Only when I finally broke past the reviews and read Seymour Hersh's book on Henry Kissinger did it become clear that it is only incidentally a book about Kissinger. "The Price of Power: Kissinger in the Nixon White House" is about Vietnam. Hersh, the dust jacket reports, took a leave from journalism to work for Sen. Eugene McCarthy's 1968 "Children's Crusade." He is still fighting the war. Hating the war--or, rather, hating the American part in it--he came to hate Kissinger. His rage, hitched to his formidable investigative talents, makes the book juicy as journalism, farcical as history.

Many of us were angry at Kissinger and Nixon in those days. Some of us now find ourselves sobered--sobered not merely by the passage of time and like corruptions but by what we have seen and learned in the interval.

The principal thing I have come to feel since the war is that Nixon's and Kissinger's choices were much narrower than we critics then commonly thought. Hersh still seems to believe some sort of reasonable negotiated settlement was available. He does not examine this belief with rigor. Nor does he define what a political compromise might have looked like. But he cites approvingly the position of people who were "against the war" from that perspective.

Was a negotiated outcome, something other than a sellout, available in the 1969-72 period? Almost nothing in Hersh's portrayal of the American or Vietnamese scenes supports a positive answer. In this country support or tolerance for the war and its assorted objectives was crumbling, and in Indochina the North Vietnamese were determined to advance.

It is not simply that the exertions of the American anti-war movement contributed to undercutting the settlement that the movement professed to favor in place of the war. Hersh's own interviews for this book, done in Hanoi in 1979, demonstrate conclusively that the North Vietnamese wanted it all in South Vietnam. It is disingenuous of Hersh, who is so quick to see a similar quality, worse qualities, in Kissinger not to pursue those interviews to their logical conclusion. He is criticizing Kissinger for not following a negotiations route that the North Vietnamese had assured Hersh would leave the United States with nothing.

True, the interviews are not conclusive. Perhaps the people in Hanoi, despite what they told Hersh, were ready to stop short of pressing their full military advantage. On the question of what Hanoi intended to do after a negotiation, however, there is another relevant body of evidence. It is the record of what Hanoi actually did in South Vietnam after the peace talks: took it over, crushed its separate political structure and seated a police state that made Thieu and company look like pussycats. Was it more complicated than that? Hersh does not address what actually happened at all.

We are getting closer to the heart of the matter. A policy based on trying to win the war could not be carried off, at either the American or Vietnamese ends. A policy based on trying to negotiate a peace was bound to crash. What else was there? Pulling the whole plug, including cutting off all aid, was also out of the question --certainly to Nixon and Kissinger.

Also to Hersh? Reporting with a sympathetic nod that Hanoi feared American-sponsored motorcycles and miniskirts were denigrating Vietnamese culture, he conveys the distinct impression that a Hanoi takeover was to be preferred to the continued rule of the "immoral" Thieu.

Some people said then, and some look back and say now, that it would have been best if the United States had coldly surveyed its interests and the odds, ended its entire direct military role, but offered Saigon aid. Any subsequent Saigon collapse would have been its own affair.

Different ones among us might have different notions of whether such an approach would have worked in terms of either foreign policy or domestic politics or morality. My point would be there was no honorable way to start down that path without being prepared to countenance an eventual communist victory at the end of it.

This is what I have against Hersh: his unreadiness to acknowledge that, however badly things were going with Kissinger and Nixon, no other available policy seemed to promise anything different from an eventual communist victory. That was the torment, and the tragedy.

There are levels of fault and error. I do not think Kissinger's and Nixon's, or Thieu's, were the worst.