It was the kind of evening Hubert Humphrey would have loved. You could almost see his eyes sparkling and that quick little smile lighting up the familiar face.

There were his friends and some who weren't always his friends; there was good food and witty repartee. And there were long speeches. They weren't as long as they might have been if the late vice president had been there, but he would have approved. They were full of substance and provacation.

It was all for him. There was even a bronze bust of Humphrey by Chaim Gross, the New York sculptor who was also his friend.

In a way, it was the second time the Woodrow Wilson International Center for Scholars had a 10th anniversary. The first one was two years ago, but that, explained assistant director George Seay, was the anniversary of the legislation establishing the center.

This year's 10th anniversary dinner marked 10 years since the center became operational. And it honored Hubert Horatio Humphrey, the center's first chairman of the board.

It was a little hard to hear because of all the applause when Vice President Mondale came into the Smithsonian Castle's dining room, but the "confrontation" went something like this:

"Hiya Henry," smiled Mondale at former secretary of state Henry Kissinger.

"Hiya Fritz," smiled Kissinger back at Mondale.

Lots of laughter.

It was a little bit nervous, this studied nonpartisanship, virtually on the eve of a national election.

But what the Republican Kissinger had in common with the Democrat Mondale was a shared love for the feisty druggist from Minnesota who was being honored by this flock of international intellectual thinkers.

Dinner had already begun when Mondale and his clutch of secret service arrived.

Nancy and Henry Kissinger had come earlier, to the pre-dinner reception in the Castle's entrance hall.

Even then the election tensions were tangible. Here were ex-Humphrey senatorial and vice-presidential aides like Herb Waters and Tom Burke, along with a clutch of Carter administration officialdom including ICA (nee USIA) director John Reinhardt and OMB chief James McIntyre. Over there were GOP heavyweights like RKO General president Frank Shakespeare and Reagan's debate negotiator Jim Baker.

Humphrey's personal secretary Vi Biglane was there, as was his sister, Frances Humphrey Howard.

Sol Linowitz, the U.S. Mideast envoy who might be secretary of state, some say, if Carter wins, was asked to pose with Henry Kissinger, who might be again if Carter doesn't.

"Ah," said Linowitz, "but will he agree?"

The pair walked into dinner arm in arm.

What about Gene McCarthy's endorsement of Reagan, Kissinger was asked.

"Well, I agree with him," said Kissinger.

"Well, I think he's a fine poet," said writer and onetime LBJ adviser Douglass Cater, "but as a political analyst . . . "

It wasn't until almost the end of the evening that Walter Mondale announced his candidacy for the presidency. At least that's what most of the audience presumed.

His speech had as its format Mondale's metaphorical application to the Center for becoming a Wilson scholar. "But," he concluded, "I'll file it in about 12 years. I have things to do until then."

The Wilson Center lives in the Smithsonian Castle along with some rare treasures, some owls and Smithsonian Secretary S. Dillon Ripley. It was supposed to be a temporary arrangement when it was agreed to 10 years ago and there does appear to be a tad of discomfort that, as Max Kampelman put it, "we came for a little dinner and never left."

Ripley too suggested that it might be nicer for everybody if the center had its own house, but that, of course, is up to planners and Congress, and there's not really much center scholars can do. Kampelman, a longtime Humphrey aide in the old days, is head of the U.S. delegation to the Conference on Security and Cooperation in Europe going on now in Madrid. He flew in from Spain to emcee the dinner.

Flanked by Kissinger and Mondale, he announced that it was absolutely not true that last night's dinner was sponsored by the League of Women Voters but that anyway, Kissinger had pledged not to talk about Iran or Stealth and Mondale wasn't going to breathe a word about pollution of trees, the constitutinality of the co-presidency idea or how many Chinas there are.

Kissinger, who might well have been Hubert Humphrey's national security adviser and the Minnesotan won his bid for the presidency, made an impassioned plea for a national consensus on foreign policy "in the spirit of Hubert Humphrey, with his bubbling optimism and his enormous faith to sustain us."

Once, he said, when Muriel Humphrey held her late husband's seat, she called Kissinger and asked about a specific vote. "What do you think Hubert would have done?" Kissinger said she asked.

Then he said, "I think if we as a nation ask ourselves that question, we cannot go very wrong."