Norway. Paraguay. Ghana. Botswana. England. Ethiopia. Switzerland. Spain. All in a space of weeks. "My passport is so thick that sometimes I'm questioned about whether it's real," says Stiglitz, who travels weekly to consult with economic leaders worldwide.

Colleagues half his age claim they struggle to keep up. But when you are trying, as Stiglitz is, to "weigh in on battles for global social justice" and "shape and rebalance the political debate"--in this country as well as abroad--well, you write eight books in eight years. Turn out half a dozen articles in a month. Travel 200 days a year. Work 18-hour days. Employ a staff of schedulers. Eat meals during phone interviews that you conduct while boarding airplanes.

Even with a Democrat in the White House, Stiglitz plans no letup in his public critiques of the wars in Iraq and Afghanistan or the policies that fostered the current economic crisis. He isn't seeking a return to Washington, though. "I will take the president's calls," he says. "But I've been through the Washington struggle to get things done, and it's not easy. I'd rather talk about the principles of sound economic policy than engage in the important infighting that is inevitable to get them enacted."

His priority is to win a more equitable share in the benefits of globalization for the billion people who live on less than $1 a day. The travel gets exhausting, he admits, and his goal will undoubtedly outlive him. But the peripatetic Professor Stiglitz doesn't tire of the work. Before he boards a flight from LaGuardia to L.A., he shares a bit of advice he often gives his students: "Don't settle for solving a small problem when you may be able to solve a larger one."