The Iraq crisis has seen George Bush supply in deeds precisely the grand new post-Cold War ''vision'' that he has repeatedly been asked for but has been unable to furnish in words since his administration took office.

The vision that the president has been making real in his policy looks to an international community led by the United States uniting on principle and on the tenets of international law, working collegially and especially through the United Nations and sharing equitably the tasks and costs of commitment.

In fidelity to basic ideals and in devotion to consultation and collective action, this policy surpasses almost anything that the most ambitious visionaries have imagined since Woodrow Wilson's time, or at least since the drafting of the United Nations Charter.

Had Bush announced early on that this was the way he intended to proceed, he would have raised eyebrows all around, especially in his own constituency. By personal experience and political tradition, after all, he and his hardheaded kind have spoken first for the uses of power and will in an East-West context.

As president, he has handled well the marvelous openings provided by the Gorbachev revolution, but this has been mainly a matter of managing change that was happening anyway under someone else's auspices, not of stirring or guiding change under his own.

Now he is reacting to the sort of disorder or, if you will, evil that many hopeful people had thought was being banished from the international scene by the emanations of East-West de'tente. It turns out, as the realists had warned, that technology, ethnicity and raw ambition still provide plentiful space and spark for massive trouble.

Perhaps more by pragmatic instinct than conscious design, Bush's response has drawn on the two distinctive elements of the post-Cold War time. One is the widespread popular expectation that reconciliation and democracy, not tension and dictatorship, now constitute international norms; there is a huge international hunger for idealism. The other element is the availability of new instruments of international cooperation to treat local problems. In particular, Soviet-American de'tente has removed the familiar bloc distractions and unlocked the previously untapped problem-solving resources of the United Nations Security Council.

But, of course, things are not so simple. Two sets of difficulties are posed by the stunning progress Bush has made toward an uplifting vision of a world at peace. One set arises if his policy in Iraq fails, another if he succeeds.

If his new internationalism fails, then Bush may face the dilemma of upping the ante unilaterally or accepting an unsatisfactory, internationally arranged result. Indeed, there are people in many places who suspect that the president has put only mock confidence in the international process and that his real intent is to seize or make a national occasion to bash Iraq. Others, who do not question his good faith, understand that Saddam Hussein may yet force Washington to a fateful either/or choice.

It may come to this. And whether the outcome then was better or worse, it would mean that the crisis had been treated not by a new vision of orchestrating the combined principled demands of many nations but by the old practice of American risk calculation and perhaps military confrontation. Bush would have lost the chance to firm up a genuinely new post-Cold War foreign policy. He would end up not with a precedent but with an experiment that had failed.

If his new internationalism succeeds, however, Bush will find himself in a strange place: committed by his very success to a style -- based on law, consultation with allies and neighbors, consensus, collective action -- which restricts the national freedom of action that American strategists have always prized.

In Iraq, circumstances have happily conspired to make the new international style useful to American interests, notwithstanding an evident tug on policy makers to keep open a more extreme unilateral military option. But one can imagine different circumstances in which the United States did not so clearly hold the high moral, legal and political cards. A president might then chafe under the ''Iraq precedent.'' Think for a minute about Panama. About Israel. And so forth.

Vision, in short, offers great value and comes at a cost. With the Iraq test still going on, it is the right moment to start thinking whether we are ready for it, or whether we can afford anything less.