THE PAST MONTHS have given us a chance to learn something about Jimmy Carter the politician, but this past week he became Carter the President. What we know of him as a man may enthrall or disgust us, but in the penal colony of our emotions, where we imprison ourselves in coolness or cynicism, it has to be assumed that hope wants to break out, at least for now. The times will get better, we will have a leader again, the country will regsin a purpose.

This moment of temporary sanity is fleeting, for sure. The beginning of presidency, when the intellectual distractions of policy are put aside, is the most passing of all political moments, a transitoriness that will survive neither the first "challenge" from Congress not the first rabbit punch from the media pack. But for a little while, hope is an emotion that need not be hidden.

It can be celebrated visibly because the presidency is still the most visible institution through which Americans work out their conflicts. It is the nation's most powerful office but also its most human; citizens can despair of "faceless bureaucrats," but the face of a President is before the public daily. Much of the rest of the governmnet beats with a metal heart, but the presidency is one human being, one focus and one set of emotions.

Is Jimmy Carter worthy of the public's hope? A case can be made that he is, if only because he comes to office as the nation begins its third century and experiences its first change in pwer in 13 years not marked by the tragedy of an assiassination or a forced retreat from office. No one has written much about it, but what are the sensitives and interior responses of the young when the only elected Presidents they known - Johnson and Nixon - led the country into turmoil? How can idealism be nurtured when Presidents, the symbols of public morality, because their trust? Why take the presidency to heart, if all its holders do is take it to hell?

Carter is not about to lead us a heavenward trip - that is one promise he didn't make - but he does have an opportunity for elevation: to raise the country's perception of the perception of the presidency, to let us see it again as an office of service. Just a sense of that would be plenty. By his programs, whether to create jobs or reduce inflation, Carter is unlikely to do anything except add a few bricks to the national wall that was allowed to deteriorate during the Nixon-Ford years. That will be doing much, assuredly, and lives will be affected. But the life of the nation involves more than jobs and money. Values matter, too.

As for the origin of these values - are they Godgiven truths or man-made visions? - Jimmy Carter told the Democratic convention last July that "a simple and proper function of government is just to make it easy for us to do good." By that statement, he was aligning himself with the philosophy of politics advanced by Plato, who wrote: "You cannot make people good; the most you can do is create the conditions in which the good life can be lived," and turned it into a synonym for hedonism. Buy it has nothing to so with pleasures, unless it is the one spoken of by those who do lead good lives - the pleasure of using one's skills or ideas in the service of others.

In his campaigning, Carter revealed that he had a sense of service. Perphaps the making of his own bed, during the primaries when he slept in voters' homes, or lugging his own suit bags through airports, were strategies of style that he adopted after staff people told him that the common man image would work. But if he is out to fool the public with gimmickry, the effort comes at a time when citizens have learned the deceits of imagery too well.

If it is the other way - that the made beds and hauled suitbags are meant to symbolize a politics coming to power who cares more for serving that being served - then such an impulse deserves to be given time to work its course. A public servant who truly believes in his servanthood may not be the answer to any of the nation's problems; "answer" are intellectual consceptions, and citizens get their fill of them from task forces, commissions, platforms and other Washington creations. But a President as Server has an opportunity to stir the nation's heart in a way that ideas can never stir its head, because his service is what keeps alive contacts with the citizens. Every President pleges an open administration and denounces Oval Office isolation, but separateness is not overcome by a rush of activities around the country. It happens by a more contemplative process, of the citizens picking up the emotions of their leader and knowing that his decisions are made on the reality of public need, not some hunches about "the public mood."

Carter has promised to be "a President who's not isolated from the people, but who feels your pain ans shares your dreams." That may be mere campaign talk, but it would be too much to bear if Carter were discovered playing games with the public's pain and dreams only to win office. He couldn't have fooled that many people.

To have a President who talks about feeling and sharing is to make it easier, at least for now, for the citizentry to risk palcing some of its hope in a human being. THis is a new feeling for many, and if a new figure and new administration were not before us, it might be a feeling top be kept inside. But an inauguration is an outisde event - for the parade along Pennsylavania Avenue and for the emotions of hope that fall in line behind the President walking it.