Only a fool or perhaps a foreigner who doesn't understand would fail to see the importance of that ritual on the glazed lawns of the Capitol yesterday.

A huge chunk of our painful history was buried, with respect. A sober sermon was preached by this new leader in the pulpit. He did not raise revered shouting and millenial fantasies. But he stirred hopefully at old dreams, the revival of an older faith.

This is incredible, certainly, against the historical realities, all the contrary dynamics that have swept the nation through so many hurtful experiences, but there it is. Knowing the web of disappointments and contradictions, knowing the prelude of debased national virtue, the countrymen still swept forward, prepared to listen and believe.

And, of course this is thoroughly American. A new President may do or fail to do so many commonplace things; his hands are pushed by events or tied down by hard realities. His spirtual power, nonetheless, remains unmatched and, on that level, President Carter entered office delivering new symbolic messages, statements of shared belief that are absorbed, almost unconsciously, by the audience.

The war is over, he told us, the one that split America apart a century ago. Jimmy Carter's mere presence at the rostrum, taking the oath of highest office in the temporary temple constructed for that purpose, delivered that message. A Georgia accent in the White House closes out five generations of bitter division enfranchising at last the white South.

But on terms which none but the wisest could have foreseen a decade ago: across the front row, in front of President Carter, were double ranks of black faces, an incredibly powerful choir that Carter brought north with him from Atlanta. They sang the "Battle Hymn of the Republic," the campfire song of righteous Yankee armies, and everyone understood.

A band from Virginia Tech marched on the White House later, playing "Dixie," followed shortly thereafter by Abe Lincoln on roller skates. Then along came the Illinois Seventh Cavalry in Yankee uniforms, looking proud about something. And th bizarrely integrated colors of the Mississippi combined college band - orange, black, red, green, white uniforms, not to mention black and white musicians. And the Alabama float, featuring the black blues of Big Chief and his Barrel House Rockers.

People died in Alabama and Mississippi and Georgia, too, over this question of race not very many years ago. Yet this new President from the South did not even need to talk about it, except in the most oblique way.The event itself consecrated the profound change that America has undergone; his inauguration raised racial tolerance to a new level of official orthodoxy.

The other side of that - the full citizenship for Southern whites - was obvious too. At the Capitol, two Alabama boys, brimming with good talk, were making themselves known to every friendly face in the crowd.

Buddy Bennett of Mussel Shoals, Ala., and his pal, L. C. Jeffries, were explaining the untapped Southern virtues of Jimmy Carter, preaching to the converted, it seems.

"We couldn't hold our heads up anywhere in the country," Bennett was saying, "if we didn't support one of our own kind, a man of the soil."

Jeffries was explaining the theological messages contained in Carter's Inaugural sermon, the humility of Christian faith. "We are all animals on this earth, seeking our way," L.C. said to a couple of frozen Yankees, who couldn't help out warm up to him.

A lady from South Carolina interrupted, in the friendliest way, when she head his last name.

"Have you got a cousin named Jeffries in Texas, works in the state department of education? she asked.

'Not that I know of," said L.C.

"Well, he's a nice man," she reported.

This was happening, remember, in the capital city, where the black majority has finally won the right to elect a black mayor, where the President's daughter will attend a public school, with an enrollment that is predominantly black. It is a profound gesture of faith in the interracial future, perhaps Carter's strongest sermon to date, and done so naturally by him and his wife that its message fulfills the old platitude - that the South would someday teach the North about race.

Against all that troubled history, this diverse assembly of countrymen came together so naturally yesterday, the bumptious and the well-born, beautiful young faces and lumpy old men, as if they were used to gathering on the Capitol grounds, listening to each other's strange accents and exchanging implicit statements of faith. They wore patriotic colors on their hats and lapels and wollen caps announcing the name of their new leader. Like Americans, they bragged about their cold feet.

Jimmy Carter, standing in his new pulpit, was careful with their faith, unlike so many of his recent predecessors. He did not promise much and, afterwards, he was praised for it. He did raise one visionary dream - a world without the curse of nuclear weapons - an idea so starting that no national politician has ever had the nerve to suggest it before. Carter promised to step toward that horizon but no one expects to reach it soon.

Instead, Carter told his audience to believe. To believe in God, to believe in family, to believe that this nation, so hurt in recent times, can once again be passionate and young about its own future.

Though expressed in modern idioms, this is old-time religion and stern stuff. America must be moral to survive, he said, the original compact made with God 200 years ago."I have no new dream to set forth today," the President announced in his peculiar clipped style, "but rather urge a fresh faith in the old dream."

And Carter offered a healing balm to his defeated adversary, the retiring President, thanking him for his efforts to erase the scandal of recent years. It was a more magnanimous political gesture than Americans have been used to seeing in recent years. It seemed to shrink the titanic and bitter conflicts that were prelude to Carter's own triumph.

Conflict will resume, of course, and perhaps bitterly because promises to test new approaches, his own, against the established way of doing things.

But, ridiculous as it seems, even a fool could imagine, caught yesterday in that mass of Americans on the Capitol grounds, tht in this country those old articles of faith are still possible. For this strange country, when a new President walks from the Capitol to the White House most anything is possible.