You are Marty Cann, and this is the moment you've feared since your family's secret got out two summers ago. It's not where you are -- an ordinary gas station in this town your family has called home since the 19th century -- it's the guy walking toward you. You didn't expect anything momentous to happen when you stopped to fill up on this summer day in 2008, but there he is, and he sees you. The two of you have said hello since all this started, but now you want to talk. You want to make things right, even though you have no idea how to do that. He's taller than you, of course -- once upon a time, he played fullback for the local high school -- but he seems almost forbidding up close, with his bald head and soul patch tilted down at you. You've got to say something. "Hey, Darrell," you blurt out. "Do we need to talk?"

You are Darrell Crawford, 39 years old, and you weren't expecting to run into Marty Cann here. But Abbeville doesn't have a lot of gas stations, so it's not exactly a shock. You are still struggling with the fact that your family tragedy has become a public discussion, but you're a preacher, so you're used to having people watch you. No one would blame you if you yelled at him, or turned your back on him, or just kept right on walking as if he didn't exist. A simple murder would be tame in comparison to what happened. You have some anger pent up, to be sure, so maybe you decide not to let Marty off the hook that easily. You smile and say, "I'll let you know."

VI. GRADUATES EQUAL GROWTH

A GREAT APPEAL of green jobs — or, for that matter, of a growing and efficient health care sector — is that they make it possible to imagine what tomorrow’s economy might look like. They are concrete. When somebody wonders, What will replace Wall Street? What will replace housing? they can be given an answer.

As answers go, green jobs and health care are fine. But they probably aren’t the best answers. The best one is less concrete. It also has a lot more historical evidence on its side.

Last year, two labor economists, Claudia Goldin and Lawrence Katz, published a book called “The Race Between Education and Technology.” It is as much a work of history — the history of education — as it is a work of economics. Goldin and Katz set out to answer the question of how much an education really matters. They are themselves products of public schools, she of New York and he of Los Angeles, and they have been a couple for two decades. They are liberals (Katz served as the chief economist under Robert Reich in Bill Clinton’s Labor Department), but their book has been praised by both the right and the left. “I read the Katz and Goldin book,” Matthew Slaughter, an associate dean of Dartmouth’s business school who was an economic adviser to George W. Bush, recently told me, “and there’s part of me that can’t fathom that half the presidential debates weren’t about a couple of facts in that book.” Summers wrote a blurb for the book, calling it “the definitive treatment” of income inequality.

The book’s central fact is that the United States has lost its once-wide lead in educational attainment. South Korea and Denmark graduate a larger share of their population from college — and Australia, Japan and the United Kingdom are close on our heels.

Goldin and Katz explain that the original purpose of American education was political, to educate the citizens of a democracy. By the start of the 20th century, though, the purpose had become blatantly economic. As parents saw that high-school graduates were getting most of the good jobs, they started a grass-roots movement, known as the high-school movement, to demand free, public high schools in their communities. “Middletown,” the classic 1929 sociological study of life in Indiana, reported that education “evokes the fervor of a religion, a means of salvation, among a large section of the population.”

At the time, some European intellectuals dismissed the new American high schools as wasteful. Instead of offering narrowly tailored apprentice programs, the United States was accused of overeducating its masses (or at least its white masses). But Goldin and Katz, digging into old population surveys, show that the American system paid huge dividends. High-school graduates filled the ranks of companies like General Electric and John Deere and used their broad base of skills to help their employers become global powers. And these new white-collar workers weren’t the only ones to benefit. A high-school education also paid off for blue-collar workers. Those with a diploma were far more likely to enter newer, better-paying, more technologically advanced industries. They became plumbers, jewelers, electricians, auto mechanics and railroad engineers.

Not only did mass education increase the size of the nation’s economic pie; it also evened out the distribution. The spread of high schools — by 1940, half of teenagers were getting a diploma — meant that graduates were no longer an elite group. In economic terms, their supply had increased, which meant that the wage premium that came with a diploma was now spread among a larger group of workers. Sure enough, inequality fell rapidly in the middle decades of the 20th century.

But then the great education boom petered out, starting in the late 1960s. The country’s worst high schools never got their graduation rates close to 100 percent, while many of the fast-growing community colleges and public colleges, which were educating middle-class and poorer students, had low graduation rates. Between the early 1950s and early ’80s, the share of young adults receiving a bachelor’s degree jumped to 24 percent, from 7 percent. In the 30 years since, the share has only risen to 32 percent. Nearly all of the recent gains have come among women. For the first time on record, young men in the last couple of decades haven’t been much more educated than their fathers were.

Goldin and Katz are careful to say that economic growth is not simply a matter of investing in education. And we can all name exceptions to the general rule. Bill Gates dropped out of college (though, as Malcolm Gladwell explains in his recent book, “Outliers,” Gates received a fabulously intense computer-programming education while in high school). Some college graduates struggle to make a good living, and many will lose their jobs in this recession. But these are exceptions. Goldin’s and Katz’s thesis is that the 20th century was the American century in large part because this country led the world in education. The last 30 years, when educational gains slowed markedly, have been years of slower growth and rising inequality.

Their argument happens to be supported by a rich body of economic literature that didn’t even make it into the book. More-educated people are healthier, live longer and, of course, make more money. Countries that educate more of their citizens tend to grow faster than similar countries that do not. The same is true of states and regions within this country. Crucially, the income gains tend to come after the education gains. What distinguishes thriving Boston from the other struggling cities of New England? Part of the answer is the relative share of children who graduate from college. The two most affluent immigrant groups in modern America — Asian-Americans and Jews — are also the most educated. In recent decades, as the educational attainment of men has stagnated, so have their wages. The median male worker is roughly as educated as he was 30 years ago and makes roughly the same in hourly pay. The median female worker is far more educated than she was 30 years ago and makes 30 percent more than she did then.

There really is no mystery about why education would be the lifeblood of economic growth. On the most basic level, education helps people figure out how to make objects and accomplish tasks more efficiently. It allows companies to make complex products that the rest of the world wants to buy and thus creates high-wage jobs. Education may not be as tangible as green jobs. But it helps a society leverage every other investment it makes, be it in medicine, transportation or alternative energy. Education — educating more people and educating them better — appears to be the best single bet that a society can make.

Fortunately, we know much more than we did even a decade ago about how education works and doesn’t work. In his book, “Whatever It Takes,” (and in this magazine, where he is an editor), Paul Tough has described some of the most successful schools for poor and minority students. These schools tend to set rigorous standards, keep the students in school longer and create a disciplined, can-do culture. Many of the schools, like several middle schools run by an organization called KIPP, have had terrific results. Students enter with test scores below the national average. They leave on a path to college.

The lessons of KIPP — some of the lessons, at least — also apply to schools that are not so poor. Last year, the Gates Foundation hired an economist named Thomas Kane to oversee a big new push to prepare students for college. Kane is one of the researchers whose work shows that teachers may matter more than anything else. Good teachers tend to receive high marks from parents, colleagues and principals, and they tend to teach their students much more than average teachers. Bad teachers tend to do poorly on all these metrics. The differences are usually apparent after just a couple of years on the job. Yet in a typical school system, both groups receive tenure.

The Obama administration has suggested that education reform is an important goal. The education secretary is Arne Duncan, the former school superintendent in Chicago, who pushed for education changes there based on empirical data. Obama advisers say that the administration plans to use the education money in the stimulus package as leverage. States that reward good teaching and use uniform testing standards — rather than the choose-your-own-yardstick approach of the No Child Left Behind law — may get more money.

But it is still unclear just how much of a push the administration will make. With the financial crisis looming so large, something as sprawling and perennially plagued as education can seem like a sideshow. Given everything else on its agenda, the Obama administration could end up financing a few promising pilot programs without actually changing much. States, for their part, will be cutting education spending to balance their budgets.

A few weeks ago, I drove to Shepherd University in West Virginia to get a glimpse of both the good and bad news for education. Shepherd is the kind of public college that will need to be at the center of any effort to improve higher education. Located in a small town in the Shenandoah Valley, it attracts mostly middle-class students — from the actual middle class, not the upper middle class — and it has a graduation rate of about 35 percent.

Several years ago, the state of West Virginia started a scholarship program, called Promise, in part to lift the graduation rate at places like Shepherd. The program is modeled after those in several Southern states, in which any high-school student with a certain minimum grade-point average (often 3.0) and certain SAT scores gets a hefty scholarship to any state school. When West Virginia officials were designing their program, though, they noticed a flaw with the other programs. The students weren’t required to take a course load that was big enough to let them graduate in four years. In some cases they were required to keep a minimum grade-point average, which encouraged them, perversely, to take fewer courses. Many students drifted along for a few years and then dropped out.

So West Virginia changed the rules. It offered a bigger carrot — free tuition at any public college — but also a stick. Students had to take enough courses each semester so that they could graduate in four years. Judith Scott-Clayton, a young economist who analyzed the program, concluded that it had raised the on-time graduation rate by almost 7 percentage points in a state where many colleges have a graduation rate below 50 percent.

Given those results, the Promise scholarship might seem like an ideal public policy in a deep recession. It pays for school at a time when many families are struggling. It keeps students busy when jobs are hard to come by. It also has the potential to do some long-term good. But nearly everyone I interviewed in West Virginia — the students, the president of Shepherd and other education officials — worried that financing would be reduced soon. The program is expensive, and state revenue is declining. Something has to give.