Michael S. Roth is president of Wesleyan University. His most recent books are “Beyond the University: Why Liberal Education Matters” and “Memory, Trauma and History: Essays on Living With the Past.”

What do you do when you see a place you love disappearing? How do you hold on to the best of it without simply becoming nostalgic? For the writer Luc Sante, that place is Paris, and the disappearance has been going on for a long time. The rich, he tells us, “have the power to save the things they love.” The rest of us must turn to the poets and the artists, the recyclers of history and memory. But we must avoid becoming merely sentimental, he warns; after all, “everything is always going away.”

Sante’s “The Other Paris” is devoted to recollection — not of the monuments and glories of the city beloved by so many, but of its underside, which has long been threatened and in recent years has become increasingly difficult to find. The author is a critic drawn to photography and literature that explore the lures of the margins, of the all but forgotten. Sante’s latest book is offered “mostly as a reminder of what life was like in cities when they were as vivid and savage and uncontrollable as they were for many centuries, as expressed by Paris, the most sublime of the world’s great cities.”

What is vivid and savage for Sante is the Paris discovered over the centuries by flâneurs, those “relentless walkers” who sometimes delighted in the surfaces of the City of Light but more often looked into the nooks and crannies where ordinary people made their lives. “For the passionate observer,” as Sante quotes the poet Charles Baudelaire, “it is an immense pleasure to make a home in the multitude, in the flux, in the motion, in the fleeting and infinite.” But Baudelaire wrote in the mid-19th century; the passionate flâneur of today must believe in ghosts, the presence of the past that neither bulldozers nor skyscrapers can completely obliterate.

Sante’s excursion through Paris is indeed a ghost tour. “The city’s principal constituent matter,” he writes, “is accrued time.” He finds traces of the past in a cityscape that has been hell-bent on modernization and where Parisian officialdom has long tried to cover the tracks of change. The most massive transformation of the French capital occurred in the second half of the 19th century, as Baron Haussmann served Napoleon III by slashing boulevards wide enough for troops to march down and by obliterating tight neighborhood spaces in which popular energies simmered and sometimes boiled over.

‘The Other Paris’ by Luc Sante (FSG)

The result was a city reconfigured for business, commerce, tourism and homogenization. Traditional neighborhoods had been sufficient unto themselves, developing their own micro-cultures and traditions. But by the late 19th century, Paris (and much of the rest of France) was accelerating down the thoroughfare of centralization and modernization.

Sante seeks to uncover the Paris that centralizing, hygienic officialdom tried to bury. He writes of hobos and gangsters, prostitutes and artisans who plied their trades along the streets. The book is beautifully designed and illustrated in a way that cultivates attentiveness. Sante is attracted to the dive bars and the squatters, the smells of the slaughterhouse and the slimy rivers running through quartiers off the beaten path. He sees a rough-and-tumble urban milieu that often did grind down men and women under forces of poverty and violence, but also represented a humane alternative to the pursuit of power and wealth that characterized the high-tone quartiers. The bohemian world had its horrors, he well knows, but he is powerfully attracted to what historian Richard Cobb called the “limitless sociability that did exist, especially between midnight and four in the morning.”

Sante catalogues the names of streets long ago erased, of tiny cafes and of dimly remembered writers. The great chroniclers are here, too, such as Hugo, Baudelaire and Verlaine. And the singers, from Thérésa to Fréhel to Piaf. These were artists whose fame didn’t get in the way of their insight into the interstices of urban life. And Sante’s book owes more than a little to Balzac, who wrote, “The streets of Paris possess human qualities, and as a consequence of their physiognomy they impress certain ideas upon us against which we are defenseless.” Sante explores the physiognomy of the other Paris — the shapes, sounds and smells that give insight into the city’s soul.

Over centuries, he says, Paris has “continued its reign as the world capital of contradictions.” These come to the fore when revolution erupts, as it did in 1789, 1830, 1848 and 1871 (to name only the most famous eruptions). For many, these were deadly affairs, and Sante reminds the reader that these political upheavals had social reverberations that can still be felt today. Indeed, he badly wants them to be felt. He wants those in power to be reminded of the powder keg of injustice and discontent on which they sit; he wants those struggling in the city to be reminded that existing hierarchies can be radically disrupted.

Since this book was published, a more brutal type of disruption has struck on the streets of Paris. Today, terrorists attack urban diversity and its possibilities for sociability in the name of their forced homogenization.

In the beginning of the 20th century, bohemians in Montmartre and revolutionaries in the Latin Quarter kept recognition of urban contradictions and the dream of limitless sociability alive. After 1945, so much had to be rebuilt; it was “a time of historical regurgitation, when all the ghosts came out maybe for a last dance.”

Sante is no pessimist, though. His heart is with the surrealists and situationists, radicals and dreamers dedicated to “finding a way to convert their daily existence into a program for the transformation of life.” That is what the other Paris has always offered its people — opportunities for transformation. Today, when the forces for conformity are both more massive and more subtle than ever, deep change may “be able to thrive only in the cracks that form in the ordered surfaces of the future.” “The Other Paris” recollects fissures from the past not as seeds for nostalgia but as provocations. The “other” city Sante powerfully illuminates may be a “dirty utopia,” but it is one very much alive with contradictions, with possibility. It must be defended.

The Other Paris

By Luc Sante

Farrar Straus Giroux. 306 pp. $28