To read Charles Maier’s new book, “Once Within Borders: Territories of Power, Wealth, and Belonging Since 1500,” is to take a bird’s-eye flight across five centuries of geopolitical history, to witness how societies have regarded and apportioned space on this planet.

As concepts of boundaries and territories are reconceptualized in the 21st century, with wars and political campaigns sometimes waged over them, the notion of what it means to be part of a particular society is taking on new dimensions. For most people, traditional concepts of nation, state, and territory remain deeply ingrained in their sense of self and belonging.

Maier takes readers on a meditative journey through the “fitful evolution of territorial organization,” and reflects on how science and technology have expanded concepts of space, authority, and sovereignty. He asks readers to consider the many ways in which human societies have claimed borders and territories to consolidate power, wealth, and group affiliation — and how those borders have shaped people’s consciousness through time.

The Weatherhead Center discussed the topic with Maier, the Leverett Saltonstall Professor of History at Harvard.

WEATHERHEAD: What inspired your interest in borders?

MAIER: It’s a fundamental fact that we don’t have one world state. And once you don’t have one world state, then the fact of borders follows tautologically, almost. So it seemed worth reflecting on that. For this book, I was struck by living through globalization rhetoric for a decade. People who talk about globalization, like [author and New York Times columnist] Tom Friedman, say that technology has a lot to do with it. I have a materialist bias in some sense. For example, railroads allowed control of space that you didn’t have before. The telegraph collapsed time to convey ideas. And when you have air travel, you see the concept of space differently. Then I started wondering, is there a politics of space?

In my earlier book, “Leviathan 2.0: Inventing Modern Statehood,” which is part of a global history, I was struck by how many countries became more cohesive and centralized in the mid- 19th century, which is not thought of as a period of epochal change. I thought to myself, “But it is, really,” and it’s based upon being able to control space to a much greater degree. And finally I was interested in the concept of empire, in part because I was worried about America.

WEATHERHEAD: Why did you choose 1500 as a starting point?

MAIER: Territorial organization is simply something that’s accompanied the modern period. And it seems to me that around 1500 is when people started rethinking borders. The advent of a decisive innovation in military technology — cast-iron projectiles for artillery — leads to the reconstruction of fortifications all over Europe and a heightened sense of state frontiers and the domains within. Medieval Europe did have borders, but it’s not clear they amounted to the same thing. [The year] 1500 is also a representative date for the European encounter with the societies of the Americas and Asia, which means a huge conceptual leap in the sense of geographical space and how it is organized.

At the end of my chapter on the “Space of States,” I talk about the cognizance of borders that appears later in fiction. You have popular 19th-century novels set in the 17th century (such as “The Three Musketeers” and “I Promessi Sposi”) that depict how their protagonists were acutely aware of borders but were trying to transcend them at the same time.

WEATHERHEAD: Don’t borders give us political organization, and, by controlling space, the possibility of a rule of law?

MAIER: You could have law that’s not territorial, in theory. You had alternatives to territorial jurisdiction and borders, such as the religious communities in the Ottoman Empire before its reforms in the 1850s. A person was identified as Jew, Orthodox, Christian, Roman Catholic, Muslim by these communities and represented as such. Territorial organization and representation is actually fairly new (in the past few hundred years) as an organizational principle. Sometimes inhabitants would think of themselves as subject to one prince or emperor, but one who did not necessarily represent a physical territory. But the legal order has been based primarily on territory until recently. That’s what’s defined it. The border ordinarily sets the territorial limit to official authority. Sovereignty, borders, legislation, and territory hang together as a cluster of concepts.

WEATHERHEAD: Aren’t borders a key factor in nationalism and self-identity?

MAIER: We sometimes think that allegiance to a place gives rise to wars. But belonging to a religion is not a great substitute, and belonging to a certain physical type is certainly a bad one. People want these feelings of belonging, however, and territorial criteria provided them fairly well, by providing a legal order and institutions, among other things.

Every marker of identity entails a division of those outside from those inside. Along with the allocation of material welfare, identity issues remain a major stake of political life, peaceful or violent. That’s why I’ve been interested in borders, because it’s where the outside/inside separates. The bulk of my book is not just about borders, but the concepts of the territorial orders that fill them. It follows the evolving practices of territoriality itself as a resource for politics and political economy. States went from an overriding interest in frontiers and sovereignty to a growing concern for the economic resources that spatial control could provide. Modern communications and transportation magnified these possibilities and changed territorial consciousness, as did imperialist and ultimately ideological rivalries. “Once Within Borders” endeavors to trace that long history.

WEATHERHEAD: Is it possible that we could live in a networked world some day without physical borders?

MAIER: Do we still need to be defined by physical borders? That’s a good question. I am not certain that we shall always require them, but I think in many ways we still do. More precisely, large numbers in our society still do — the groups we increasingly define as populist — and that was the brunt of my conclusion.

The “network” is a spatial analogy or metaphor that emerged even before World War II, but thrived thereafter. Nineteenth-century developments such as the railroad and telegraph and undersea cables gave us the images of lines cutting through space, whether on the map or in such concepts as electromagnetic lines of force. The network became a dominant metaphor when urban and national electrical grids, multiple switching possibilities, computers, and then the internet grew dominant throughout the 20th century.

Everybody’s using the network now as a metaphor. But if we are doing so as a way to say we don’t need states, then I think that’s somewhat utopian. There’s a wonderful anthropological parable by Italo Calvino in his book “Invisible Cities.” In one of the fantasy cities that his narrator Marco Polo describes to Kublai Khan, residents erect a post alongside their houses, which they then connect to other house posts according to the relationship they have with the people in the other houses. So blood relations are tied together by a particular color of rope, economically related households get another color, friendships a third, and so on. And then one day they all decide to move on. They take down their houses but they leave the posts and the colored ropes. So the traveler arrives to find all the posts with connecting lines that reveal the quality of the relationships but no dwellings or people. It is the perfect parable for the networked community. The city is gone but the network remains.

We love spatial metaphors. Our concepts of territory have usually correlated with physical science possibilities. Science suggests ways of thinking about space. For example, the period of constructing fortifications and frontiers that resisted artillery sieges also saw the development of ballistics, Newtonian physics, and the development of calculus. Nineteenth-century nationalism, which focused on penetrating the state and mobilizing human and industrial resources, ran parallel to concepts of energy fields that filled space. And the network makes perfect sense in an age of computers.

WEATHERHEAD: Do you think borders will eventually go away?

MAIER: I’ll never say never. People still want frontiers: Look at the election returns. There’s a certain comfort in them. When I started thinking about the ideas in this book, I thought that borders were coming down all over, that we were moving toward a borderless world. The fall of the Berlin Wall remained a vivid memory. Going into this project, I assumed territory didn’t matter as much as it had earlier. Well, that was innocence. Now I think that if borders are fading, they’re fading slowly and with a lot of pushback.

WEATHERHEAD: What do you think about Donald Trump’s pledge to build a wall to keep out Mexicans?

MAIER: I can’t imagine for the long-term future that walls are going to be up again in a solid, durable way because I think we are entering a period of much more interchange of peoples. The Hungarians built a wall. Donald Trump wants to build a wall. But I don’t think they do much good. Each movement generates a counter-movement. The point I try to make in the end of the book is that borders are one thing, but it’s what happens inside borders and territories that matter. As long as there are vastly unequal life chances in different societies, you are going to get a flow of people. But we can’t control people like we can control water flow through a dam. Until we can figure out a way of evening out income to a tolerable degree across the world, we’ll get immigration.

WEATHERHEAD: Can populism be seen as a result of stronger identification with national boundaries?

MAIER: This whole phenomenon that we call populism, which I think is a problematic designation, is part, I believe, of a deeper failure of institutions, a profound dissatisfaction of vulnerable groups with their political institutions or civic life.

Somehow we are observing a detachment from public efforts and institutions that dates from the end of the 1970s. That does not mean that people are less political — rather that the traditional collective groups that channeled political life have ceased doing so with anywhere near the same binding energy. I’d like to try to explain why these traditional associations worked more effectively before the ’70s and why less so since then. Albert Hirschman, a wonderful economist and social scientist, wrote a provocative essay called “Shifting Involvements” about the tidal oscillations of public and private passions. He claimed that people were being perpetually disappointed, first in the public sphere and then in the private, or vice-versa, investing their energies in a pendulum-like search for fulfillment.

My sense is that the first two-thirds of the 20th century saw one massive public cause after another in many countries. The developed world went through colonialism, the First World War (followed by some “relaxation” in the 1920s), then a renewed mobilization of society to struggle through the Depression, then to fight World War II, and then to enlist for the Cold War. We use the metaphors of war all the time for our public causes. I think other societies do as well, and some of the causes have been quite bad, like fascism and Stalinism. But then at some point it’s as if our societies questioned the purpose of this confrontational life. Whether through private life or alternative political (but noninstitutionalized) movements, they began to desert official commitments and most recently have come to see those who still speak for the old elite channels as totally corrupt. I would like to account for this great movement historically — narratives are a form of explanation — but I have not yet figured out how to make this an inquiry that can be answered in a convincing way.

WEATHERHEAD: What do you hope readers will take away from your book?

MAIER: The policymaker won’t learn whether to build up borders or tear them down according to this book. It would be nice to think that reading history provides policy guidance. But almost by definition, the historical world is an overdetermined system. The real policy contribution the historian can offer is to make the reader aware of the prevalence of surprise and the complexity of developments. Reading good history should achieve the effect of listening to good music. At the end of it, I hope the reader is more in tune and mentally enhanced. I don’t want readers to take away a particular point but a sensibility, as if they’d read a revelatory poem or listened to a great symphony.