American public rhetoric is highly self-conscious. One can sense it in the stilted speeches of the presidential hopefuls, who have not quite hit their campaign stride. They are searching for the right turn of phrase, the evocative formula, that will give them the necessary rhetorical lift.

In many ways their problem is exacerbated by the unprecedented prosperity and global success of the United States today. Poor George W. Bush and Al Gore are reduced to allusive references to American greatness beyond mere tangible material achievements. In the absence of any pragmatic challenges, politicians are thrown back upon the rhetorical essence of the nation.

They must invoke the spirit of the Fourth of July for the next year and a half. Without cover of serious policy proposals, since only marginal improvements are possible in our collective well-being, we are compelled to reflect more and more on the meaning of America. But this is of a piece with the whole tradition of its founding. Where other nations could take assurance out of the knowledge that they had always been, America knew very distinctly that it had a beginning. No myths of primeval ancestors forming the nation time out of mind could relieve the anxiety of knowing that America had originated in the actions of men.

Other nations can find national purpose in the mere fact of their existence. America is not sure it even has a national culture, and it is regarded by the rest of the world as identical with generic modernity. It has no alternative but to find its raison d'e^tre in the explicit moral commitments of its foundation. Americans are often accused of going on moral crusades as if this was a personal failing that could just as easily be avoided. The truth is that America itself is a moral crusade. If it ever ceased to be driven by a moral purpose it would cease to be America. It would cease to be a nation.

The problem is that the symbolic resources available for transcendent public evocations are extraordinarily limited. It is not that our politicians are hollow or deficient. They are compelled to invoke the sense of national greatness with nothing more than the sonorities of rhetoric itself.

Still, this period can be a golden opportunity for contemplating the deeper meaning of the country's foundation. Within this breathing space in history, where no pressing emergency distracts us, opportunity is offered for a refounding of America that would deepen and enlarge the moral inspiration from which it springs. A redoubling of efforts, not toward greater prosperity or power but toward greater mutual understanding would provide the world with a far more resplendent city on a hill.

The American Founders and refounders were very much conscious of the character of their experiment. It was nothing less, Hamilton remarked, than the determination of the most important question of "whether societies of men are really capable or not of establishing good government from reflection and choice, or whether they are forever destined to depend for their political constitutions on accident and force."

The problem was, as the Framers also recognized, that the resources for shaping this self-governing society were of necessity rather thin. Gone were all the great authoritative institutions of aristocracy and church that could convey a stabilizing influence by virtue of their prestige and independence. Increasingly government had to depend on the self-restraint and rationality of individual citizens as its sustaining source. Even the presence of generalized Christian ethos has been successively evacuated from the public square where citizens meet in their political capacity.

As a result, the experiment in liberty has been pushed to the point where it seems to exist in splendid isolation from anything else. The logic of contracting public rhetoric toward its bare essentials has proceeded virtually to its limit. We are inclined to wonder today whether the great experiment in self-government any longer means anything. Is liberty simply a great black hole to be filled with every caprice imaginable to the human mind?

An experiment that had liberty as its inspiration and goal now is compelled to confront the implications of its logic. Can the exercise of liberty be sustained if it is no longer clearly connected with any substantive good? The crisis of "liberalism" is now synonymous with the vacuum in public rhetoric.

Will America and its leaders be up to the new challenge of showing the way forward toward the refoundation of liberty beyond liberalism? That is the question on which the presidential election and the new century turn. Success will depend on our ability to grasp the secret of what has made the tradition of liberty a world historical success. Rhetoric will find its true resonance when its practitioners have learned to touch the inner chords of American greatness.

It has never been the empty clang of a do-whatever-you-want celebration of collective egoism. Liberty has rather been a compressed symbol of all that is great in the human spirit. The longing for service toward what is ultimately good without diminution of qualification remains. We may no longer be able to name exactly the transcendent source of this pull, but we are as capable as ever of experiencing its attraction. The experiment in liberty will be best sustained by those who are best able to evoke its highest purpose.

The writer is a professor of politics at Catholic University.