Of France's 62 million people, fewer than 5 million are old enough to have any memory of the horrifying weeks in May and June 1940, when the Nazi war machine crushed the country's armed forces, forced them to sign a humiliating surrender, and marched triumphantly into Paris. The blitzkrieg, and the traumatic occupation that began 70 years ago Monday, are rapidly sliding below the horizon of living memory.

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That makes it easy to see the France of 1940—which was poor, rural, homogenous, and overall quite religious—as a wholly different place from the wealthy, urbanized, multicultural, and deeply secular France of 2010. They appear, prima facie, to be radically different places. But look closer, and it's easy to see that, 70 years later, France is still very much, well, France.

That's not to say things haven't improved. By today's standards the country in 1940 was almost unrecognizably poor. Half the population still lived in rural areas, with a quarter of the workforce still engaged in traditional forms of agriculture—peasants, by any other name. One third of all French households lacked running water, and less than one 10th had telephones, refrigerators, or washing machines. In the winter, the courtyards of urban apartment buildings bristled with shelves on which the denizens stored their perishables. Hotels advertised hot running water as a luxury item. Today, despite persistent high unemployment, France has a successful, high-tech, postindustrial economy largely fueled by nuclear power and symbolized by the high-speed train system that whisks travelers between Paris and London (via the Channel Tunnel) in just over two hours.

The great institutions that dominated much of French life in 1940 have mostly withered or collapsed altogether. While more than 40 percent of adults and a large majority of children attended church regularly in 1940, today the figures have fallen by more than half, and in one recent poll, only a bare majority of the population even described themselves as Catholic. The number of priests in the country has declined from more than 40,000 to fewer than 10,000. At the other end of the ideological spectrum, the Communist Party that once dominated the industrial working-class suburbs of major cities—running the municipalities and organizing much of the communal life—now polls below 5 percent of the vote. The military, once one of the most important and prestigious French institutions, has become almost invisible to civilians—especially since the end of the draft 10 years ago.

France in 1940 ruled one of the largest empires the world had ever seen. Its tricolor flag flew over most of North and West Africa, a chain of possessions stretching from Polynesia to the Caribbean, and most of Indochina. Legally, the Algerian coast was considered part of France just as Hawaii today is considered part of the United States. It had vibrant French businesses, schools, and cultural life (one of the century's greatest French authors, Albert Camus, hailed from Algeria). But the empire dissolved in the great wave of decolonization in the 1950s. Algeria and Vietnam won their independence in desperate guerrilla wars, and more than a million European settlers fled back across the Mediterranean from North Africa. Today, France overseas is a dim constellation of small island possessions: Martinique, Guadeloupe, Réunion, French Caledonia, Saint-Pierre.

And yet, despite all these changes, certain things about French society have remained remarkably constant since the blitzkrieg, particularly in comparison with the United States. Most important, the French state retains an outsize role in society. In a tradition of dirigisme (from the verb "to direct") that stretches back to the Old Regime, the state encases markets in thick webs of regulations while itself managing health care, most major cultural institutions, and most education from preschool to postdoctoral. When President Nicolas Sarkozy took office in 2007, conservative American observers hoped he would emulate Margaret Thatcher and slash the state sector. But despite some tentative reforms, the state's authority remains largely unshaken (government expenditures consistently account for more than 50 percent of GDP, compared with barely 36 percent in the United States before the recession). And as in 1940, the most attractive career track for smart, ambitious students is the elite civil service. As a French friend once put it to me, "Most of my classmates would rather become assistant secretary of agriculture than start Amazon.com."

Then there is the outsize role of intellectuals in French life. It has undoubtedly frayed at the edges since 1940, and no French thinker today enjoys anything like the oracular status of a Voltaire, a Victor Hugo, or—in the 1940s—Jean-Paul Sartre. Yet even pretenders to the throne, such as the philosopher Bernard-Henri Lévy, receive far more media attention than their American counterparts. How often was Richard Rorty on network television? French magazines continue to publish gossipy "hit parades" of top intellectuals.

Needless to say, France remains the worldwide center for luxury goods that it has been for centuries. Even today, its exports of perfumes, alcohol, clothing, accessories, and beauty products match its aerospace exports (which include Airbus). Fine food is still central to the country's identity as well, even if the artery-clogging recipes of Auguste Escoffier, still hegemonic in 1940 (including 39 separate recipes for butter), long ago gave way to the healthier nouvelle cuisine. And while the French consume less than half the wine per capita than they did in 1940, adults still manage an average of 70 bottles a year—nearly seven times what Americans consume.

These tastes testify to a certain cosmopolitanism that was central to French culture in 1940, remains central to it today, and has been accompanied by a remarkable openness to the world. France's poor, restive immigrant populations today receive a huge amount of press coverage, but they are in fact nothing new in French history. Between 1918 and 1945 France actually welcomed more immigrants—measured as a percentage of the population—than any other Western country, including the United States. What distinguishes today's immigrant groups from those of 1940 is not their numbers, but their origins. In 1940 immigrants were largely white and Catholic (coming notably from Italy, Poland, and Iberia). Now the country has a black population of more than 1.5 million, and a Muslim one of about 5 million, largely of North African descent. It has hundreds of thousands of Asian citizens, and in some areas of Paris, asking for "baguettes" in a restaurant will not produce the familiar long loaves of bread, but the other food-related item to which the French word refers: chopsticks.

And both in 1940 and today, immigration has been the occasion for furious outbursts of prejudice and agonized debates about "French identity." In 1940 the worst outbursts were directed at the Jews, and they set the stage for the anti-Semitic policies of the collaborationist Vichy government, which willingly sent 76,000 French Jews to their deaths in the Nazi extermination camps. Today, the far less noxious but still objectionable National Front party derives its support largely from hostility to French Arabs, and the debates focus on whether the secular republic can "integrate" Muslim populations. The Sarkozy administration has wrestled awkwardly with the issue, creating a Ministry of Immigration and National Identity, and trying to ban women from publicly wearing burqas. Concerns about "Islamicization" are in fact mostly exaggerated, and the anger expressed by young French Muslims (for instance, in the massive 2005 riots around depressed housing projects) results less from a generalized hostility toward French society than toward the isolation they feel from it.

The debate over immigration is passionate and intense. But in its very passion and intensity it reveals yet another continuity between 1940 and 2010—namely that the subject on which the French speak most eloquently, and most engagingly, is still themselves.

Bell is professor of history at Princeton University and author of The First Total War: Napoleon’s Europe and the Birth of Warfare as We Know It.