That news abhors a vacuum and will instantly fill it with anything from anywhere is hardly new, but seldom has that truism been more apparent than in recent weeks in Washington.

The new Congress convened Jan. 3, quickly took its oath, signed on the public payroll and swiftly departed for more congenial climes, on official vacation. For the last three weeks its members have been circling the globe at public expense presumably in search of significant information to help them govern later, mending fences at home and attending to myriad other personal tasks in the public interest all the while being far removed from Washington.

Dare we say it? With the exception of the Social Security efforts, truly significant, nothing's been going on.

But if anything, the absence of Congress has only added to the torrent of news pouring out of the capital. With nothing else to write about, as ever the news mill has been grinding exceedingly small and fine. We've had leaks about the budget and other messages to come, leaks about the size of the deficit, none of them coming as any surprise, leaks about the forecasts of national economic growth, at least as politically motivated in nature as they are soundly based in scholarship, leaks about the administration's political strategies, real and imagined, and assessments about the assessments about the assessments.

All of these last, of course, have been weighty (and, yes, this corner has contributed its ponderous share to the pile). The collective opinion about Ronald Reagan that emerges from them is not too surprising, either, given the record. As Arlo Guthrie said, in another context, "He's been inspected, detected, and rejected." Now the president has weighed in with his own self-appraisal. He's pronounced everything splendid, says he wouldn't change a thing and awards himself an all-around "A" for performance.

With all this happily behind us, the true political world of Washington begins anew as the new Congress returns. There, the capital and the country face the prospect of real change and momentous news.

It is not too much to suggest that some of the heaviest responsibilities to be borne by American lawmakers since World War II will fall upon the shoulders of this new Congress. The range and complexity of problems confronting them are immense and crucial.

Fundamental questions about the nature of the American and world economy, about striking a balance between assisting citizens in dire need and paring government expenditures simultaneously, about bringing down the historic high federal deficits without tipping the country into a depression and still maintaining America's strength, about forging new policies to assure the viability of our alliances and equally to build a new relationship with our old adversary, the Russians--all are coming due all at once. They cannot be postponed. For better or worse, this next Congress must address them.

Perhaps above all else, this new group of lawmakers has an even more difficult task. It must demonstrate that our political system is capable of responding to the great demands upon it and thus repair the widespread belief, false or not, that our governmental machinery and national decision-making processes are floundering.

In the face of such an agenda, given the cynical public view of congressional performance and the record of the last such group to assemble here--one characterized by ideology, insularity and selfishness--the immediate inclination is to throw up one's hands and say, "Are you kidding? No way."

Yet this Congress takes up its burdens in an atmosphere that generates new hope. It holds the promise of being more realistic, possessed of a more tested, surer leadership, and, one hopes, an accompanying broader, more disinterested view of national and international problems.

An assessment of its prospects by Horace Busby, the Washington political consultant and former Lyndon B. Johnson aide, is especially noteworthy. Busby finds the new Congress in marked contrast to the old.

"Two years ago," he writes, "when the 97th Congress convened, the atmosphere was alien. Republicans and Democrats had not split the two houses since 1930. Nobody knew how to make the alignment work. In the Senate, Republicans were muted about their new majority; none had ever been in the majority, had ever served as a committee chairman. For that matter, no Democrat in the Senate had experienced being in the minority. It was a strained, tense time.

"Adding to the tenseness, mainstream Republicans found themselves surrounded by exotics from outside the party: anti-abortionists, school prayer activists, NCPACs, the Moral Majority and all kinds of quick-trigger ideologues. These groups claimed responsibility for the 1980s' GOP agenda. Democrats, too, had problems of this kind when they discovered that, wonder of wonders, there were actually Democrats in their midst calling themselves 'conservatives.'

"This is all changed now. Republicans and Democrats have learned from experience that they can work together. The majority position in the Senate has blooded a new and impressive generation of GOP leadership, now the single most important force in and upon national policy. In both houses, GOP leadership has moved swiftly to reclaim their party from the chokehold of fringe elements. This encourages optimism."

Heavens forbid, a good word for Congress. But I think Busby is right. While the White House may deprecate the congressional leadership, especially among GOP ranks, as members of the "College of Cardinals," one rests easier with people of the stature of Howard Baker, Bob Dole, and Pete Domenici leading the Senate and a Congress in which both House and Senate have been strengthened by the addition of moderate, practical politicians on both sides of the party aisles.

That's real news.

NOTE: A recent column, describing an encounter on a crowded rush-hour Metro train from Capitol Hill, brought an unusually heavy response. I described seeing a young blond-haired man wearing a gray warmup jacket bearing the words "The Jews Killed Christ" emblazoned across the front and with what appeared to be blood running down one side of his face, although it could have been, I thought, stage makeup.

A number of people saw the man approached by a young woman demanding that he take off his jacket with its offensive words. When he refused, she struck him repeatedly with an umbrella, drawing blood. Throughout, the man remained impassive, even pleased, one person thought, by provoking a violent reaction, and then entered the car on which I was a passenger.

Among many letters received, one woman's reaction is worth sharing:

"Such a strange feeling came over me--everything around me seemed so different when I saw him that I didn't know whether I was awake or dreaming. I was alone. I could hear myself lecturing him in my head, screaming at him--the language of rage. What I did, however, was stare at him to see if there was really a human being in there. When my train came I sat in my seat, and watched that man disappear from sight as we rode away. But that wasn't the end of him! I was so mad at myself for not having said anything to him! I actually had a nightmare that I believe was directly attributed to the sight of him and I have not had a nightmare in years . . . . You said that incident 'may deserve no more than a passing notice,' but you noticed it and I noticed it. It certainly affected me. I'm sure it was not the emotion this fool had intended to incite. Thank God I had the 'good sense,' as you put it, to keep silent--or I may have had the regrettable sense to shove him in front of an oncoming train."