The advice is all very practical. But it’s also a little pat and, as that salute to smiles as a social leveler suggests, naïvely patronizing in a way that’s worth examining. Critics of public diplomacy have been quick to disparage the American belief that international tensions can be eased by dispatching an official to proclaim that deep down we are all united by our love for, say, children — a Hughes staple — when the animus, in fact, arises from real policy differences with the U.S. government. The pursuit of private diplomacy rests on the opposite innocent illusion: just tone down crass Americans’ noisy cultural differences from others, and political and economic harmony can follow. But what if Americans have no monopoly on brashness and don’t really rate any longer as the overweening cultural trendsetters our demonizers, and we, reflexively assume?

In essence, the mission of the American as World Citizen is to try and fit in better, or at any rate to stick out less: just what the U.S. as a nation is resented for making no attempt to do. But it’s hard to know which of our features cry out for modulation. Does Turkey, a proudly secular and deeply devout society, distrust us for our wild popular culture or for our moralizing piety? Whatever might be the case, a mere 17 percent of respondents registered a positive image of Americans, according to a recent Pew survey, and only 3 percent expressed confidence in Bush, putting Turkey at the top of the list of U.S. detractors. Meanwhile, two recent pop-culture sensations — a pulp thriller called “Metal Storm” and a film called “Valley of the Wolves” — feature the U.S. military as marauding invaders. Paradoxically enough, the Turkish forces who take brutal revenge resemble nothing so much as their nemesis. There isn’t much difference, it seems, between the Hollywood invasion thriller and the anti-Hollywood invasion thriller.

What may be most confusing of all is the warm welcome U.S. visitors actually receive in a country that is as culturally cacophonous as America and labors under no inhibitions when it comes to boasting and bullying. The demurely dressed American tourist (shoulders and knees covered, often in khaki) can’t walk a block in Istanbul without seeing Turks wearing hijabs and jilbabs (those modest coatdress coverings) side by side with tank tops and tight jeans — and without getting lectured about where the true cradle of cultural diversity lies. Here’s a collision of secularism and Islamism, the Turks are right, that owes more to Ataturk and centuries of entanglement with Europe than to the corrosive allure of New World exports.

Busily monitoring our well-known tendency to strident self-importance, earnest American practitioners of personal diplomacy can risk missing the genuinely humbling lesson of being abroad: an awareness of how bewildering another country’s own blend of boorishness and fervent belief, of openness and defiance, of backwardness and progress and of internal dissensions can be. In the end, it’s as narcissistic to assume we’re the overbearing cause of everybody else’s national identity crises in a dizzying world as it is to imagine that we can orchestrate the solutions to them. The sobering, and liberating, truth is that our britches are not that big.