If the population of this country were a person, the doctor would have put us on anti-mood-swing medicine long ago. I'm assuming that there is such a drug and that it would have spared us the dizzying cycle of highs and lows we have undergone in relation to our feelings about Ronald Reagan. Of course we go through this with all our presidents. The Jimmy Carter who is much praised for walking, not riding, down Pennsylvania Avenue at his Inauguration becomes the wimp. The Gerald Ford who is briefly revered for toasting his own English muffins becomes the klutz. Merely to stir these recollections is to give at least some hint of where the problem lies: in the things we choose in the first instance to admire our leaders for.

But there is more to it than the superficiality of our standards or the fickleness of our affections, which leads us, if the polls and public comment are to be believed, to an endless, almost manic reassessment of our presidents. They're the best, they're the worst, they're great leaders, they're jerks. Right now, for instance, in Washington and, by reports elsewhere in the country, Reagan is being characterized, again, as out of it -- feeble of grip on the office, unequal to the job, finished. He has been so characterized several times before, once, notably, after his first debate with Walter Mondale, when a lot of people wrote him off.

Some part of this recurrent negative diagnosis is no doubt political, made by those who fervently wish it to be true. And some part is owing to real events -- failures and scandals that in fact happened and for which the administration in general and the president in particular are accountable. But Reagan (like Carter and Ford and the rest of them) is after all basically the same man from month to month, and it would be easier to credit these periodic plunges into the political basement if, in between, he didn't seem to rise again. A year ago, no longer the dodo of critical estimate, he had been recharacterized as a strong, sure and popular leader, and the lush Fourth of July celebration at the Statue of Liberty was a sort of third inaugural. Now he has been re-dodoed. My suspicion is that he has at least one return to the critical heights left in his term, probably in connection with a U.S.-Soviet summit and an arms-control agreement.

The problem with peaks-and-valleys analysis is that it is not credible (neither the peaks nor the valleys) and it keeps you from spotting what may really be wrong. I'm not questioning the existence of current trouble -- no one in his right mind could pretend that the president isn't in a heap of it now -- but rather the overwrought interpretation of it. Certainly the past eight months or so have been pretty terrible for Reagan -- bad luck, bad calls, bad press and some spectacularly bad acting in government. Even without all the extraordinary episodes -- the saga of Donald Regan, the Daniloff embarrassment, the did-they-or-didn't-they hash of the Moscow Embassy Marines, the Deaver, Wedtech, Iran-contra and other investigations -- the last couple of years of an administration, especially an eight-year administration, would have been a time of political reckoning, letdown and fatigue. And that time is surely here. But it is to misunderstand what has happened, I think, to infer from all this that Reagan (right on schedule, peak-and-valley-wise) has become (again) the president who can't hack it, who doesn't know beans about the job, who has permanently lost political altitude and is simply looking for a place to crash-land.

What has in fact happened is that a couple of these events have eroded the single most valuable, indispensable asset a president can have: his authority. Unless Reagan can repossess it, the administration will not be able to pull out of its downward plunge.

The two events (or clusters of events) that have done most to undermine that authority, in my view, were, first, the Reykjavik meeting, with the subsequent explosion of contradictory explanation by administration officials and, second, the revelation of the grotesque arms deals with Iran. I don't say that the other business was OK. Certainly the contra subterfuge, now so much in public view, wasn't; but it at least seemed to comport with the administration's own political beliefs and logic, to flow from them. The other affairs did not. The problem wasn't that the president couldn't explain them; it was that they couldn't be explained. And with each it was also the case that you felt some missing central weight; they were all staff meeting and no decision; they were policy camels -- the proverbial beast that is a horse thought up by a committee; they were a lethal combination of impetuosity and unresolved or badly resolved internal disputes.

People sense these things. The public has a much better filter for what is important and what is merely press talk or political fragging than those who do the talking and the fragging suppose. And I think it was these events in particular that called Reagan's authority into question. The quality itself is an intangible one that cannot be prescribed and which does not come out of legal charters and empowerments or from having a preponderance of guns. Strong men (Marcos, the Argentine generals, et al.) can get dumped when they lose it. So can duly elected officials who may continue in office until the end of their allotted terms, but if their authority is severely diminished, they will be eaten for breakfast by their political opposition or manipulated by powerful aides. You don't need to get too mystical about it. There are examples. Two women, Margaret Thatcher and Corazon Aquino, different in so many other respects, exude it, some personal amalgam of certainty, confidence, capacity to prevail and unbreakable will. They have demonstrated that this, not some transformation of their housewifely habits, which they both retain, is the key to political success.

I don't believe that Reagan has gone to pieces any more than I will believe that he is king of the world when he has his next upswing in our public mood. I do believe he has sustained -- permitted -- a harmful diminution of his presidential authority. He has let too many people in his administration get away with too much. He has acquiesced (and engaged) in too much impulsive behavior and has consequently had to backtrack too often. There's no way his last couple of years will be a picnic -- the running down of energies and the running out of the political clock see to that. But he could recapture some of that lost political force and make those years a lot better than they bid to be right now.

1987, Newsweek, Inc. Reprinted by permission; all rights reserved.