A year ago tonight (April 28), President Reagan scored an oratorical triumph that presaged a great political victory. In his first public appearance since the attempt on his life, Reagan came before a joint session of Congress to make a dramatic and effective plea for his budget and tax program.

Swept forward by waves of applause from both sides of the aisle, Reagan asked the rhetorical question: "Isn't it time we tried something new?" Within three months, Congress--responding to the public pressures he generated-- had enacted "something new," deep budget cuts and even deeper tax reductions.

That occasion is worth recalling now, a year later, as a reminder of the psychology of a bygone era. How different was it? Here are three answers from the newspapers of that week.

Then, Sen. Bob Packwood of Oregon, the chairman of the Republican Senatorial Campaign Committee, was predicting great gains for the GOP in the 1982 election because polls showed millions of disaffected Democrats being drawn by Reagan's leadership into the GOP. Last month, the same Packwood infuriated the White House by saying that Reagan's positions on equal rights for women and civil rights for minorities were damaging the party severely. "We are losing them in droves," he said, of working women. "You cannot write them off and the blacks off and the Hispanics off and the Jews off and assume you're going to build a party on the white Anglo-Saxon males over 40."

Then, it was front-page news that a group of "boll weevil" southern Democratic congressmen were ready to bolt party lines and give Reagan effective control of the House on economic issues. "The Democratic Party (in the House) is not representing our interests," Rep. John B. Breaux (D-La.) was quoted April 26, 1981, as saying. "Fiscal philosophy is the dividing line. If I voted against the Reagan budget . . . people would say Breaux is tryng to stop Reagan's effort to bring back fiscal sanity."

Last week, the same John Breaux told the same Washington Post reporter, Margot Hornblower, "The climate this year is different. Our group would vote down the president's budget. The deficit is too high. The cuts are too high in areas which have already been cut. Defense spending is too high."

The mood of Congress that week of 1981 was captured in a story T.R. Reid wrote for The Post: "Liberal fire met conservative ice in a House hearing room yesterday, and the result--for so great is President Reagan's strength on Capitol Hill right now--was predictable: budget director David Stockman skated easily through the heated attacks of liberal critics. With cool, almost icy, assurance, Stockman set forth before the House Education and Labor Committee the administration's proposals for cutting back various education, job-training and school lunch programs."

Stockman's statistics were challenged; Rep. Peter A. Peyser (D-N.Y.) said, "You're in the wonderful world of make-believe." But Stockman coolly rejected the charge, leading committee Chairman Carl Perkins (D-Ky.), who had come to Congress when Stockman was a 2-year-old, to say of the stubborn, precocious witness, "If he says he doesn't believe our assumptions, I don't suppose he's going to change his mind."

Stockman made only one concession that day; he promised, as Reid wrote, "to extend his austerity decrees to the Defense Department, which has so far escaped unscathed. . . ."

"Their turn is coming next," Stockman said. "There's so much waste in the defense budget it's taken us a little longer to figure it out."

These days, Stockman is much less visible, perhaps because the whole world knows--thanks to William Greider's Atlantic interviews--that those were "make-believe" figures. And it knows that Stockman was blocked from attacking defense "waste" and ordered instead to submit a defense budget that piles a 17 percent increase on top of last year's 25 percent boost.

A year after he lit the fire under Congress to pass his budget and tax package, President Reagan is saying it is too soon to judge the results. He is saying that, because of all the measures that he cited as crying out for urgent action--interest rates, unemployment, real earnings and business bankruptcies--only one is not measurably worse today: the rate of inflation.

Referring to the span of time from his election to his address to Congress, Reagan said a year ago: "Six months is long enough. The American people now want us to act, and not in half measures. They demand, and they have earned, a full and comprehensive effort to clean up our economic mess."

The Packwoods and the Breauxs have recanted; the Peysers and Perkins have seen their judgment vindicated; the Stockmans have retreated into prudent silence.

But the president persists, and so does the "economic mess."