"Eat the rich, feed the hungry." "Occupy Wall Street, Not Afghanistan." "The Left Never Left." "Take the Bull by the Horns." "The Beginning Is Near." "The Empire Has No Clothes." "Frack Me, Frack You." "I am a revolting citizen." "Jesus was a Marxist." "Auto-plants fill the Earth with Machines Designed for Death." "I love this goddamn country, and we're gonna take it back." "We are the 99%."

These were some of the signs I saw on Saturday when I visited New York City's Zuccotti Park, the base camp of the Occupy Wall Street movement, which boasts a kitchen, clothing dispensary, health clinic, media center and lots of cool music. For weeks Occupiers have fanned out through New York City protesting—well, they are protesting many things, as the diversity of signs makes clear. But here is how a flier handed to me by a young woman at an "Information" table described the movement:

"Occupy Wall Street is an otherwise unaffiliated group of concerned citizens who have come together with the general purpose of holding Wall Street (as the drivers of an increasingly undemocratic power structure) accountable for their fiscal recklessness and criminal perversion of the democratic process. We are a bunch of people like you and me who came together and said 'enough'! We will not remain passive as formerly democratic institutions become the means of enforcing the will of only 1-2% of the population who control the magnitude of American wealth."

The Occupiers emphasize that they have nothing in common with the Tea Party, which as they rightly note identifies with an era "before the end of slavery, before the workers' rights movement, before the women's movement, before the civil rights era, and before the environmental movement." The Occupiers are resolutely nonviolent (the same cannot be said of New York police, who have pepper-sprayed some Occupiers), and they have been inspired by the recent democratic uprisings in Tunisia, Egypt and other Arab nations.

The crowd, which included people of all colors, ages and sartorial styles, gave off a strong 60s vibe—and as a peacenik who marched against the Vietnam War, I mean that as a compliment. I also sympathize with the Occupy Wall Street complaints, which have inspired similar protests elsewhere across the country and even overseas. The power of money is subverting democracy, allowing an elite few to enrich themselves while many struggle to get by with low-paying jobs or no jobs.

I have a humble suggestion for the Occupiers. They should consider reading The Price of Civilization (Random House), the latest book by Jeffrey Sachs, an economist at the Earth Institute at Columbia University, long-time consultant to the United Nations and former columnist for Scientific American. Sachs was once an unabashed believer in the benefits of capitalism. In fact, early in his career he was faulted for advocating that Poland, Bolivia and other struggling nations rapidly adopt free-market principles, an approach that critics dubbed "shock therapy."

Over the years, Sachs has become increasingly concerned with those left behind by modern capitalism. His first two books—The End of Poverty (Penguin, 2005) and Common Wealth (Penguin, 2008)—focused on the plight of the world's poorest people, especially the billion or so defined as "extremely poor," living on less than two dollars a day. Sachs spelled out ways in which we can eliminate extreme poverty while also preserving the environment. In The Price of Civilization, Sachs turns his sights on his own country, the U.S., which he believes is in peril.

"The American economy," he writes, "increasingly serves only a narrow part of the society, and America's national politics has failed to put the country back on track through honest, open, and transparent problem-solving. Too many of America's elites—among the superrich, the CEOs, and many of my colleagues in academia—have abandoned a commitment to social responsibility. They chase wealth and power, the rest of society be damned."

Sachs, like many of us, feels let down by Barack Obama. "The President," he says, "has continued down the well-trodden path of open-ended war in Afghanistan, massive military budgets, kowtowing to lobbyists, stingy foreign aid, unaffordable tax cuts, unprecedented budget deficits, and a disquieting unwillingness to address the deeper causes of America's problems."

Sachs fleshes out our plight with data. Compensation for CEOs, which in 1970 was 40 times the average pay of workers, was 1,000 times greater by 2000. The gap between rich and poor is greater than at any time since the late 1920s, just before the Depression. Meanwhile, the IRS allows powerful corporations to "hide their profits in offshore tax havens." Even Google, which is supposedly so hip and progressive, engages in a "tax dodge." According to Sachs, Google funnels billions in profits into off-shore subsidiaries, which pay lower tax rates than the U.S. corporation does. Sachs points out that Sergey Brin's "ingenious work in creating Google's search engine" was supported by the National Science Foundation, which means that our tax dollars helped Brin get his start.

Sachs's book is loaded with information and anecdotes like these, as well as with proposals that would make it harder for the powerful to rig the system for their benefit. If you want to change the system—and you should, whether or not you share my admiration for the Occupy Wall Street movement—read this book by someone who knows how the system works. Or rather, doesn't work.

Photograph of protestor at the Occupy Wall Street base camp in New York City taken by Valerie Cates.