TO JUDGE by Jimmy Carter's performance in dealing with the 95th Congress, his political education is proceeding apace. He came to Washington rather like an emissary - in his own mind perhaps an emissary of all the people - to a strange foreign capital on whose institutions and mores he intended to impose his own superior design. He found that the establishment was fragmented and parochial, resistant to designs not of its own hand, and more than a little disrespectful of interlopers who did not grant easy legitimacy to traditional political styles.

Mr. Carter has had the wit, however, to diagnose his own shortcomings, of which the largest was the failure to convince either his partners or adversaries in government that he accepted the need to employ the full powers of his office. No less important, he was able to turn events to his own advantage. The upshot is the hard-won respect in which he is basking now that the 95th Congress has gone home. He is widely perceived to be a "presidential" president at last.

Now, domestic performance - especially, bargaining with Congress - is the chief measure by which Washington, if not the country at large, sizes a president. This is a particularly appropriate standard to apply to Jimmy Carter, who came to the White House at a relatively tranquil international moment, determined to apply himself first at home.

Mr. Carter nonetheless was quick to accept a number of high-risk foreign-policy challenges. In the Panama Canal treaties, the Mideast arms vote and the Turkish arms embargo, he rejected counsels of political caution and acted according to what he (and we) felt were necessary international lights. He won on each of those issues> the demonstration of purpose and success more than compensating for the bruises. And from the highest-risk foreign venture of all, Camp David, he has emerged with a stunning personal triumph that enhanced his stature precisely as he turned back to his domestic program as the 95th Congress was counting down.

Already, to be sure, Mr. Carter had begun to receive the considerable political benefits flowing from the public mood associated with Proposition 13 - the desire to curb public spending, the growth of government and inflation. He harnessed that mood to sustain key vetoes and cut other measures back.

But Mr. Carter has done more than flow with the tide. In his approach to his own staff, the press and public, as well as the legislature, he has adopted many of the tactics by which presidents traditionally seek to blend their individual vision of government with the cluttered collective vision of the Congress.He has also stopped demanding that Congress overhaul just about every major social program simultaneously. It is not, however, that he has caved in entirely to the "old" politics. What ostensibly savoy politician would, for instance, have vetoed a public-works bill or undertaken a serious civil-service reform? It was in his own way that he finally came to terms with the 95th Congress. That augurs well, we might add, for his relationship with the 96th.

From the point of view of the national interest, the results in legislation were more than good. Arguably, the country has a better grip - if not yet a satisfactory grip - on those of its problems amenable to the legislative process than it did a few years ago. We commented yesterday on key economic issues and will comment on other issues in days to come.

From the point of view of the president, the results may have been even better. Mr. Carter fought effectively enough, and carried enough of his program, to put down the earlier widespread questioning of his presidential "competence." The political benefits to himself and his party are obvious. But he did more: His strong finish makes it possible, for the first time at least since Lyndon Johnson's political heyday, to imagine that the American system can enjoy the crucial element of a strong president. Heaven knows that's not all the American system needs. It needs a more focused Congress, a more responsible party system . . . one could go on. Jimmy Carter, though, is on the way to making his own contribution. It could be substantial.