The burst of national joy set off by release of the hostages expresses a constant theme in American life. It is the theme of isolationism, and its reemergence at this time shows how careful the new administration must be in its efforts to revive this country's influence in the world.

Mention isolationism, and people think of the dead past. There comes to mind the image of the scowling senator heaping curses on dirty foreigners. But isolationism can wear a smile as well as a frown. It has an enduring logic. It springs naturally from the American setting.

The United States is a continent that was made into a country. That achievement has at all times been supremely absorbing. Americans are a busy, throbbing people. We are ceaselessly buying and selling, always learning and teaching, constantly on the move. So why fritter away resources and energies in silly squabbles in faraway places? Better by far to cut entangling ties and be self-reliant at home.

That spirit came to the surface with all its force in the public reaction to the freeing of the hostages. Americans thought first and foremost of what was close at hand and individual. There were the hostages themselves. There were steadfast wives. There were forlorn children and bewildered parents.

For all of them, release was the end of an ordeal -- an unmitigated blessing. Inevitably, those who toiled to achieve that end felt elated. Predictably, those who reported the event became excited. Not surprisingly, those of us who watched were caught up in the excitement. Understandably, the highest officials of the outgoing administration wanted to associate themselves with the event. Rightly, the new president, on being told of the release, said: "Thank God."

So, by those degrees, the release of the hostages became a kind of national epiphany. It was almost as we had won World War II all over again.

To critize that reaction would be churlish. Still, those who think in terms of power discern a different reality. The seizure of the embassy and of the hostages was an illegal and unprovoked offense. Iranian officials then used the hostages in a shameless way to promote themselves and jerk the government of the United States about as if it were a yo-yo. Statesmen and countries dependent on American protection repeatedly saw Washington throw down the gauntlet, and then back away. In the end, those who had humiliated this country were rewarded in a shabby payoff conducted in the atmosphere of a last-minute auction.

Judged from that point of view, the national rejoicing is a scandal. Instead of celebrating, Americans should have been thinking of the continued bad relations with Iran. They should have been worrying about security problems in the Persian Gulf and the probability of another energy crisis. They should have been fretting about the disastrous effect the payment of ransom will have on those who used to look to the United States for their security. Indeed, what was a day of celebration should have been a day of mourning.

Rightly or wrongly, however, those who think of national power do not hold absolute sway in America. Ours is not a country dominated by imperial yearnings, nor military pretensions. There is no enduring majority for adventures in remote places -- especially if they take a toll in blood and money, and when their purpose is not clear. On the contrary, the American people temper instincts of power with the isolationist impulse.

So the hostage experience defines in a deep way the foreign policy mandate of the Reagan administration. There are limits to the enthusiasm for rebuilding forces and pushing other countries around. There are boundaries to the support for the projection of American political influence abroad and the application of economic muscle. o

The new administration can assert itself abroad only after carefully counting costs. It must think hard about distances -- especially psychological distances, as measured from Walla Walla, not Washington. It must weigh interests and be sure they are transcendent. It must mobilize opinion for objectives that are well understood. And then, if it does decide for action, it must be absolutely certain to act effectively. i

In that connection, an aspect of Ronald Reagan's debut arrests attention. Into the inaugural address, as into impromptu talks he gave at two private dinner parties, he slipped stories of heroism by virtually unknown soldiers. That is not a bad way, when strategic options are unclear and defense funds tight, to promote what this country most needs to feel about its record abroad -- a sense of respect.