Watch a 1940s or 1950s movie set in New York City -- noir, comedy or melodrama -- and you are sure to spot him: strap-hanging on a crowded subway car, buying a newspaper at a kiosk or sitting in a coffee shop.

The anonymous man in uniform is a stock extra in these films, as elemental to the urban landscape as the beat cop, the woman with the baby carriage or the couple in love.

But today, a woman or man in military uniform dining in a restaurant, sitting on a bench in Central Park or walking up Broadway constitutes a spectacle.

I have witnessed this firsthand whenever one of my military colleagues and I have taken West Point cadets to the city to attend a performance or to visit a library or museum. My civilian clothes provide camouflage as I watch my uniformed friends bombarded by gratitude.

These meetings between soldier and civilian turn quickly into street theater. The soldier is recognized with a handshake.

There's often a request for a photograph or the tracing of a six-degrees-of-separation genealogy: "My wife's second cousin is married to a guy in the 82nd Airborne."

Each encounter concludes with a ritual utterance: "Thank you for your service."

One former captain I know proposed that "thank you for your service" has become "an obligatory salutation."

Dutifully offered by strangers, "somewhere between an afterthought and heartfelt appreciation," it is gratifying but also embarrassing to a soldier with a strong sense of modesty and professionalism.

"People thank me for my service," another officer noted, "but they don't really know what I've done."

Sometimes, the drama between soldier and civilian turns plain weird.

One officer reported that while shopping in uniform at the grocery store one evening, she was startled by a man across the aisle who gave her an earnest, Hollywood-style, chest-thumping Roman salute.

My friend is unfailingly gracious, but she was entirely at a loss for a proper response.

These transactions resemble celebrity sightings -- with the same awkwardness, enthusiasm and suspension of normal expectations about privacy and personal space.

Yet while the celebrity is an individual recognized for a unique, highly publicized performance, the soldier is anonymous, a symbol of an aggregate. His or her performance is unseen.

The successful reincorporation of veterans into civil society entails a complex, evolving process.

Today, the soldier's homecoming has been further complicated by the absence of a draft, which removes soldiers from the cultural mainstream, and by the fact that the current wars in Iraq and Afghanistan have little perceptible impact on the rhythms of daily life at home.

Whether anyone ever spat on an American soldier returning from Vietnam is a matter of debate.

The sociologist and veteran Jerry Lembcke disputed such tales in "The Spitting Image: Myth, Memory, and the Legacy of Vietnam."

Apocryphal or not, this image has become emblematic of an era's shame, and of the failure of civilians to respond appropriately to the people they had sent to fight a bankrupt war.

The specter of this guilt -- this perdurable archetype of the hostile homecoming -- animates today's encounters, which seem to have swung to the other unthinking extreme.

"Thank you for your service" has become a mantra of atonement. But, as is all too often the case with gestures of atonement, substance has been eclipsed by mechanical ritual.

After the engagement, both parties retreat to separate camps, without a significant exchange of ideas or perspectives having passed between them.

When I broached the subject with a major with whom I had experienced the phenomenon, he wrote a nuanced response. Although he's convinced that "the sentiments most people express appear to be genuinely FELT," he nonetheless distrusts such spectacles.

"Does the act of thanking a soldier unconsciously hold some degree of absolution from the collective responsibility?" he asked.

No reasonable person would argue that thanking soldiers for their service isn't preferable to spitting on them. Yet at least in the perfunctory, formulaic way many such meetings take place, it is an equally unnatural exchange.

The ease with which "thank you for your service" has circumvented a more enduring human connection doesn't bode well for mutual understanding between soldiers and civilians. The inner lives of soldiers remain opaque to most of us.

"Deep down," the major, who served in Iraq, acknowledged, "my ego wants to embrace the ritualized adoration, the sense of purpose, and the attendant mythology."

The giving and receiving of thanks is a seductive transaction, and no one knows that better than this officer: "I eagerly shake hands, engage in small talk, and pose for pictures with total strangers."

Juxtaposed in his mind with scenes from Fallujah or Arlington National Cemetery, however, his sanitized encounters with civilians make him feel like Mickey Mouse, he confessed. "Welcome to Disneyland."

Thanking soldiers on their way to or from a war isn't the same as imaginatively following them there. Conscience-easing expressions of gratitude by politicians and citizens cloak with courtesy the often bloody, wounding nature of a soldier's service.

Today's dominant narrative, one that favors sentimentality over scrutiny, embodies a fantasy that everything will be OK if only we display enough flag-waving enthusiasm. More than 100,000 homeless veterans, and more than 40,000 troops wounded in action in Iraq and Afghanistan, may have a different view.

If our theater of gratitude provoked introspection or led to a substantive dialogue between giver and recipient, I would celebrate it.

But having witnessed these bizarre, fleeting scenes, I have come to believe that they are a poor substitute for something more difficult and painful -- a conversation about what war does to the people who serve and to the people who don't.

There are contradictions inherent in being, as many Americans claim to be, for the troops but against the war. Most fail to consider the social responsibilities such a stance commits them to fulfilling in the coming decades.

Few Americans have understood more clearly the seductions and inadequacies of professing gratitude than Abraham Lincoln.

Offering to a mother who had lost two sons in the Civil War "the consolation that may be found in the thanks of the Republic," Lincoln nevertheless acknowledged "how weak and fruitless must be any words . . . which should attempt to beguile" her from her grief.

Expressions of thanks constitute the beginning, not the end, of obligation.

Elizabeth Samet is a professor of English at the U.S. Military Academy and the author of "Soldier's Heart: Reading Literature Through Peace and War at West Point." This article was distributed by Bloomberg News.