Tourists are the ones with the Nikons around their necks. Modesty is a picture of one's self fully clothed. War is that child in Vietnam, running in terror from the napalm that blazes on her back.

Between 1839 and 1914, as chronicled in The Photographic Experience by Heinz K. Henisch and Bridget A. Henisch, the invention, development, and acceptance of photography laid the foundation for these modern attitudes. Photography changed the way the world looked at travel, at virtue, at war -- at uncountable other aspects of society and culture, even art. "Photography touches our lives, directly and indirectly, in an immense variety of contexts," write the Henisches.

The Photographic Experience reflects the medium's ubiquity and social importance: The Henisches wrote not "a standard history of photography," but "instead focused on how the Victorians received this marvelous invention, fell in love with it, and wove it into their lives," explains Heinz Henisch, research professor of physics and the history of photography.

In some ways, photography simply extended and expanded the role of the older graphic arts, woodcut and engraving. As the Henisches wryly note, "With one of those flashes of insight that mark the progress of the human race, it had been found that photographs of pretty girls could be used to sell absolutely anything, from phonographs in Brisbane, Australia, to Simmons College in Boston."

Yet in other, sometimes surprising ways, photography was an agent of social change.

Travelers, for instance, were no longer pioneers. "The photographer took pictures of scenes that visitors were expected to see, and the tourist soon felt an irresistable compulsion to add those sites to his life-list," the Henisches write. The appropriate souvenir, of course, was a photo. "Photographs came to be accepted with a complex mixture of dependence and resentment. The photographer always seemed to be one step ahead of other people, shaping expectation, forestalling discovery."

The cult of celebrity, or "the publicizing of the private self," can also be traced to the Victorian photo-shop. By the 1880s, the Henisches write, shop windows "displayed faces with no claim to fame except good looks and good background. Society figures who, a generation earlier, would have shuddered at the thought of exposing their portraits to the common gaze, now were quite happy to win in this way a little notoriety and a little cash. . . .

"Ordinary citizens discovered that photography had made it possible for them to star in their own Christmas cards, or smile at their guests from the side of their own teacups.

"Each tiny act of assertion, whether sweet or silly, was a hint of new aims and new needs. The lure of the spotlight grew, and in the glare old virtues lost their luster; reserve and modesty were thrust aside in the rush for center stage. . . .

"What would have been regarded as unthinkably vulgar in the very recent past had become an accepted, if not always approved, feature of late Victorian life: the advertising of the self."

Society's attitude toward war was also changed. When the first photojournalists covered their first wars, the Henisches write, "The public was dazzled, and then, such is the contrariness of human nature, disappointed. Photography showed so much and yet so little. The elaborate war paintings that had shaped responses up to this point had been packed with figures, live with the drama of rearing horses, clashing sabers, heroic charges, poignant farewells. By contrast, early war photographs were so empty, so still."

To capture more of war's reality, as well as more public reaction, photographers soon began shooting corpses. "There was shock, but there was also interest, and the presence of corpses in one view whetted an appetite for more in the next.

"Photographers began to feel the tug of temptation, and to aim for an arresting image rather than a literal truth. During the American Civil War, some who made pictures of a battleground after an engagement did not hesitate, here and there, to alter the position of a body in order to create a more striking scene."

Yet this sensationalism had a curious effect. "The portraits of very ordinary men, which photography made available in unprecedented number and variety, brought home to the civilian population the vulnerability of their subjects."

Earlier battle paintings "had sheltered the viewer from shock by veiling particulars." Photographs, on the contrary, had recognizable faces. As one London art critic said, "This idea of the individuality of the soldier is very new to the modern mind, because from our habit of reading histories written purely from a general's point of view, and counting men in great totals of five or six figures, we think no more of them than we think of this or that particular sovereign in Rothschild's purse."

With the advent of photography, such objectification of war was no longer possible. "Whether war was enjoyed as high adventure, or denounced as criminal folly," write the Henisches, "it was embodied, in society's imagination, in the figure of the ordinary soldier." And today, thanks to the photograph, in the image of the innocents caught in the crossfire.

The Photographic Experience, 1839-1914: Images and Attitudes was published in 1994 by Penn State University Press. Heinz K. Henisch, Ph.D., is research professor emeritus of the history of photography in the College of Arts and Architecture and of physics in the Eberly College of Science; he is a fellow of the Institute for the Arts and Humanistic Studies. Bridget A. Henisch is author of Fast and Feast: Food in Medieval Society (Penn State Press) and Cakes and Characters (Prospect Books, London). The Henisches are at work on another photo-history book, The Painted Photograph, 1839-1914.