Extreme caution by the outside world distinguishes the present phase of the recurrent Polish crisis. The general restraint indicates that, while nobody can admit it, there now exist in Europe a harmonious balance of power.

In that context, the grievances raised anew by striking Polish workers can perhaps be worked out through concessions from the Warsaw government. If so, an indent can be made against the time when age forces a change in the Soviet leadership. But if not, the whole world is into deeper trouble.

Theoretically, Europe should be a vortex of turbulence. A divided Germany lies at the heart of a divided continent. To the east are authoritarian regimes led by Communist parties dedicated to centralized economic control. To the west are open regimes with market economies. Each side does violence to the beliefs of the other every minute of every hour of every day.

But national interest transcend ideological preferences. As A.W. DePorte of the State Department has pointed out, in a recent pamphlet on the "superpower balance," the division of Europe answers the security needs of the major powers.

With Germany split, Russia faces no threat to its preeminence as a land power on the continent. France and Britain and their smaller allies feel able to contain West Germany ambition within the European Economic Community. The East European can look to Western Europe as an economic and cultural counterweight against Soviet imperialism. The United States finds in rapport with the West Europeans a solid base on the continent.

Weighed in that balance, the issue of labor troubles in Poland is truly trivial. So all the outsiders have moved to defuse the present crisis.

Russia started by announcing that the works of the Polish leader, Edward Gierek, were being published in the Soviet Union. That was an unmistakable way of saying Moscow was leaving matters up to him. Only subsequently, when Gierek's position seemed in doubt, did the Soviet leadership begin to collect in Moscow and show signs of genuine concern.

The United States reacted with studied calm. Secretary Edmund Muskie said: "Internal problems in Poland are for the Polish people and the Polish authorities to resolve." President Carter said: "We are being very reticent . . . in expressing our views."

In Western Europe, the Vatican, which is crucial because Pope John Paul is a Pole in touch with the hierarchy of his country, counseled restraint, Chancellor Helmut Schmidt of West Germany canceled a projected trip to East Germany to prevent the Polish troubles from becoming an issue in either of the two Germanys.

Settling the Polish dispute, even with all outsiders showing restraint, is not child's play. The Polish workers have demonstrated impressive unity and great tactical skill. Still, having extracted concessions by strikes in 1970 and 1976, there is a tendency to get heady about how much the traffic will bear. This time they have demanded free trade unions and more press liberty -- two conditions that lessen the control of the party in Poland, and do not exactly obtain in the Soviet Union.

On the other hand, the regime has already guided Poland far down the path to economic liberalization. The country enjoys private agriculture, trade unions that are not total stooges and exposure to the international economy. At the first sign of trouble, moreover, Gierek first changed negotiators and then purged half his cabinet.

Now negotiations have been joined, and a way out is visible. Gierek and the Russians could probably sit still for more autonomous trade unions in Poland. The Russians could probably let Gierek go and put in his place a figure more dedicated to economic liberalization.

But at some point the Polish workers will have to take their gains and call it quits until a new opportunity for pressure presents itself. Otherwise, the Russians will feel obliged to move in. The United States and Western Europe will stand by impotently. The chance for liberalizing Eastern Europe from within will be dealt a hard blow. The more so since any such set of developments would inevitably tip the leadership change due to come soon in Russia against liberalization and toward a continuation of steady military expansion.