A society reveals its values as well as its age through the choice of a national birthday.

For many Americans it is simply The Fourth. Frenchmen have their Bastille Day. The phlegmatic of the world, such as the British, avoid revolutionary reminiscing altogether. They make the monarch's birthday or some other neutral event the center of their National Day celebrations.

Some Third World countries go to the other extreme: They use independence day oratory to commemorate liberation struggles that occurred largely in myth. It is necessary to give crowds something to cheer other than a distantly remembered decision by a European government to haul its flag down and run up a new banner chosen by its local political allies.

Modern history's two most enduring political revolutions and the republics they created celebrate their national days in July. While Americans explode fireworks and char burgers on their Fourth, the French are laying in the wine and planning neighborhood dances for their Fourteenth.

The perpetually illuminating contrast between these two revolutionary siblings is more than social. France commemorates a glorious, dramatic event: the destruction in 1789 of the king's prison and armory by mobs in search of arms and vengeance. America marks a different moment that enshrines its national identity: the signing 13 years earlier of a document.

The United States is a nation "spoken into existence" and "fashioned out of ideas," historian Page Smith has written. The Fourth of July puts and keeps words at the core of the national American experience. We celebrate the declaration of a political promise, made by a landed gentry long since disappeared, to guarantee "life, liberty, and the pursuit of happiness" to those recognized as citizens.

The French and other Europeans are too experienced to take political promises that seriously. Promises commit only those who believe in them, not those who make them, one contemporary French politician has observed. Charles Pasqua did not intend that as a description of America's underlying political ethos and strength, but it serves nicely: Americans as a group continue to believe in those words, if only to measure constantly and precisely how far their society falls short of delivering on them.

Continuing and renewing the belief is a purpose worthy of a national birthday party, especially on this final annual stocktaking of the 20th century, which seems to find many Americans harboring contradictory moods and impressions about their country.

A record-setting prosperity continues to lift balance sheets and swell bank accounts. The mountain of national debt that only a few years ago seemed poised to crush the republic's vitality is now projected to shrink to zero in a decade and a half. And yet public opinion polls show that a majority of the population thinks the country is "on the wrong track."

Has America baked a sour apple pie for its birthday party?

Too much can be made of such poll results. Taking statistical snapshots of a complex societal state of mind is tricky business. Connecting them to the impact of individual events or factors such as the Littleton shootings or presidential misconduct is guesswork.

The 223rd national birthday party is a time to take a longer and broader view. In his 1980 book, "The Shaping of America," Page Smith suggested that there is a natural and constant tension in the American character shaped by the gap between the promise made by history and the reality of the present moment:

"It was one thing to declare a nation; it was something vastly more complex to accomplish it. . . . It was primarily words that held the nation together. Having been defined by words, it had to be constantly redefined, articulated, spoken, explained."

Or explained away. The tension between the words of liberty and the fact of slavery had to be resolved through bloodshed before the United States truly became a nation. It was then reshaped by massive waves of immigration that brought forth a constantly self-examining, self-critical society that still believed in promises of larger equality for all.

The Fourth of July is a day for Americans to relax, enjoy and remind themselves of how much of the promise remains to be redeemed. It is as Yogi Berra said on meeting the Jewish mayor of Dublin: Only in America.