The president's ex-speechwriter approaches the utterance of each sentence with the kind of caution a master jeweler might bring to a gem-as if the slightest miscalculation will reduce it to worthless shards.

James Fallows is being particularly cautious now, after several days of watching the 15,000 carefully crafted and meaningful words he wrote about Jimmy Carter in the current issue of the Atlantic Monthly reduced to a handful of the most pungent in the piece. Words like "arrogance," "complacency," "insecuirty," and "willful ignorance," that he used to describe the president have floated to the top of many of the accounts of the article entitled, "The Passionless Presidency: The Trouble With Jimmy Carter's Administration."

"Let me think how to say this," he says. "Under ideal circumstances, I would have preferred to let my article speak for itself." But an ideal world is not one that includes wire services, which he feels have done the most disservice to his piece. When their stories broke this weekend, Fallows found himself on the phone with reporters from Milwaukee to Melbourne, trying, "with some promiscuity, to defend my point of view."

He found himself on the phone to Jody Powell as well. "Just to prove I do have some discretion," he won't say what was said. James Fallows went to the Georgetown library yesterday to escape the clamor of his constantly ringing phone. "I sure as hell haven't enjoyed the last two days."

Earlier, in the well-appointed living room of his home on Reservoir Road, he had said, "I'm placing my hope in the idea that people will read what was written.I felt there had to be a decent and honorable way to make an important point about what was going on in the White House. So much of what has been written in the past has been tasteless."

James Fallows has tried to do it differently. No kiss-and-tell tales. No screeching denunciations. No romans a clef. At 29, he is the bright young man faced with the ex-Washington insider's eternal dilemma: how to mete out his praise and criticism and not receive the scarlet letter of the ultimate outsider-his judgments devalued by cries and whispers that a trust has been betrayed.

He is asked to summarize the point he wanted to make. "That Jimmy Carter is a good man as opposed to a . . . " He stops. "Let me phrase this correctly. That he is a good man who does not know the skills needed to be effective and who is surprisingly unconcerned about acquiring those skills."

The article praises Carter's virtue and his intelligence, while questioning whether such virtue is its own reward. It criticizes the president for his inattention to history, his blindness to the "bureaucratic perils" that might sandbag his high hopes for his correspondingly high office.

Fallows, has not strewn his article with anecdotes but there are a few personal glimpses of Carter in action. Fallows writes:

The president would "pore over budget tables to check the arithmetic, and, during his first six months in office, would personally review all requests to use the WhileHouse tennis court."

Carter listening "from 9 p.m. to long past midnight on a steamy summer night," to Ralph Nader as he "distilled into three hours the lessons of a dozen years."

The tone is moderate, but the impact is inevitably powerful, coming as it does from one who, for two years, was close enough to know.

Form of Betrayal?

"I don't think I betrayed anyone," Fallows says. "They may feel that I have-after all, I was eating their bread for two years-but I don't think that I did."

There has been no official comment from the White House, although Fallows sent an advance copy of the piece to the president long before it hit the newsstands. But Fallows says he has talked to more than two dozen of his former colleagues and many of them have said. "Don't tell anyone I said this, but you're absolutely right."

The reaction among some second level White House aides is more ambivalent. No one wants to be quoted. No one even wants his quotations in quotation marks. What they say, however, is that what Fallows wrote is accurate. Some of them also say, however, that he was wrong to write it.

Fallows' perspective, or so their argument goes, is a completely inside one. The article could not have been written by an outsider. It would have been a wonderful internal memo. But it wasn't. I was a magazine article and its publication makes their work all the more difficult. It will be damaging to the president, the argument continues, not on a point of principle, but on points of procedure.

And yes, some say, that is a form of betrayal.

All of which is very much an insider's point of view, a loyalist's argument. That role has always seemed foreign to Fallows, who has no several occasions turned his lucid and elegant prose on himself and his won actions. He is a man who starved himself while a student at Harvard to stay out of the draft-and then wrote an article castigating himself for the elitism involved and the shame he felt afterward.

His former boss and mentor Ralph Nader came in for his own share of Fallow's criticism after Fallows had worked for him on several projects. And, at one point, Fallows exchanged a Washington-based magazine free-lancing career for two years as a writer for the Texas Monthly while his wife, Delborah, finished her graduate work in lingusitics at the University of Texas.

And perhaps the questions of inside and outside, of loyalty and criticism, have been defined somewhat differently in the postwar, post-Watergate era that made blind loyalty as untenable as blind ambition.

No Harm Intended

Fallows disagrees with those who think his article will damage Carter's chances to serve a second term. "I did not want to do harm to a man who has been very good for me," he says. "I think most people will see that the intent was not to damage. I'm not deluded that a year and a half from now anything I have to say will have much of an impact."

To some, this explanation sounds naive-particularly since Fallows could easily have waited until after the next election if he was bent on doing no harm to his former boss. Particularly when he says, when asked why he didn't wait, "at the risk of a certain sappiness, this is not a Mom and Pop grocery store I'm writing about. I'm talking about things people should know about before making their choices."

There is a casual arrogance about a statement like that, and Fallows is not always unaware of it. He is 29 now, and age has laid only the lightest of resolutions on a face that has always looked younger than it is.

Bright Young Man

Behind him there is Harvard and a Rhodes scholarship and his apprenticeship to Nader. With him now is a marriage, a young son and a promising career as a journalist. In those halcyon, early days of the Carter presidency, he became, for some observers, the archetypical Bright Young Man, a symbol that the anitwar generation had come inside, to bring their idealism and talents to the service of a self-proclaimedly iconoclastic administration charged with its own energy and disdain for policis as usual.

He had walked into the glittering maw of presidential politics at the age of 27 in part because he liked the things that candidate Jommy Carter had to say to people like himself. "He would tell people that those who have had great privilege have a great responsibility," he says. And pauses. "By any objective standard, certainly I have been very fortunate."

How will the president react to the acticles? The president, he says, should find few surprises in it. He had made most of the factual points in memos to Carter, although the character analysis that forms the body of the piece had not found its way onto the president's desk. And there are few flashy, revealing anecdotes. It was a deliberate decision in deference not only to discretion, he explains, but in an attempt to keep the press from reducing his analysis to a sexy little paragraph or two. An attempt doomed from the start, as it turned out, and some observers say, as Fallows should have known it would be.

"I can't claim to be surprised, but I was disappointed at the way the wires handled it," Fallows says. "Others who have written about the article after reading it have been pretty fair. That piece took about three months," he says. "It was not something that was undertaken casually."

He is asked what he hopes the article will accomplish, since vengeance and vindication have been ruled out. "It's unlikely," he says, "that it will have any effect on the conduct of govrnment, but I think the piece reflects the feelings that many people in government have. As a cog in the machinery of government, you have very little power to move the spectrum of perceived ideas. I was struck by the comparatively enormous influence a column or an editorial or a magazine article could have."

There have been improvements, he says, in the months since he stopped working in the White House. Carter, he adds, has become more sophisticated in his dealings with Congress.And his speeches are better. "The writing seems less cannibalized," he says.

Some White House observers attribute the difference to the presence of media consultant Gerald Rafshoon and his ability to shepherd the important speeches through to their delivery more or less intact. Fallows himself says, "I was not influential enough with Carter. I'd only worked for Carter a few months when I became the speechwriter and Carter mainly trusts those who have worked for thim the longest. Unfortunately, there weren't that many people around who were his equals in age and experience. And to challenge the way he wanted to operate-that's what he needed his peers for. It's not a coincidence that they're not there."

Lessons Learned

But yes, Fallows would vote for Carter's election, as he will explain in the second installment. "It was probably vain to hope that he could be as moral as Jesus and as effective as Machiavelli," Fallows says. "I thought there would be more of the second. But his great undeniable strength is his ability to learn from his mistakes and to improve."

That is the text. There is a subtext, one that concerns the kinds of lessons any young man or woman learns when first confronted with the byzantine contradictions posed by a career in any large organization, lessons learned in a different light and with a different meaning when it is the presidency and not a private corporation that is teaching them.

"I didn't expect the organization as a whole to be so compartmentalized," he says now. "If you suggested something that was not in your specific field-a memo on the volunteer Army or public health-it became clear that that was not what I was hired to do." The memos, he said, were simply greeted with "benign indifference."

There are few regrets. Presidential trips abroad spark fond memories, even though an overly developed fondness for foreign policy is one of the facets of the Carter presidency which he criticizes quite harshly. "It was a wonderful way to see the world, even if you were a steerage-class passenger as I was."

And for Fallows, there is what there has always been for bright young men, archetypical or otherwise-the future. "I can be far more influential in the world of ideas and events in journalism that I ever could be in government," he says.

"I've said what I have to say. And 20 years from now I will be gladder to have written it than not." CAPTION: Picture, no caption, By Harry Naltchayan-The Washington Post