9/11 was a signal that we were living in a new world - a world of interdependence, a world in which people could attack the United States not from the outside, but from the inside. It was a sign that the United States, the most powerful country in the world, could watch the cathedral of capitalism at the Trade Center and the heart of its defense at the Pentagon be struck internally, not really across borders, so that borders don't matter anymore.

The real lesson of 9/11 that I think we have still to learn is that this is a world of interdependence, in which all of the challenges of environment and climate change, of jobs, of disease, of war and terrorism, are cross-border problems that cannot be met one nation at a time.

When it comes to acid rain or oil spills or depleted fisheries or tainted groundwater or fluorocarbon propellants or radiation leaks or sexually transmitted diseases, national frontiers are simple irrelevant. Toxins don't stop for customs inspections and microbes don't carry passports. North America became a water and free-trade zone long before NAFTA loosened up the market in goods.

McWorld is a product of popular culture driven by expansionist commerce. Its template is American, its form style. Its goods are as much images as matériel, an aesthetic as well as a product line. It is about culture as commodity, apparel as ideology. Its symbols are Harley-Davidson motorcycles and Cadillac motorcars hoisted from the roadways, where they once represented a mode of transportation, to the marquees of global market cafés like Harley-Davidson's and the Hard Rock where they become icons of lifestyle.

I divide the word into learners and nonlearners. There are people who learn, who are open to what happens around them, who listen, who hear the lessons. When they do something stupid, they don't do it again. And when they do something that works a little bit, they do it even better and harder the next time. The question to ask is not whether you are a success or a failure, but whether you are a learner or a nonlearner.

9/11 was a signal that we were living in a new world - a world of interdependence, a world in which people could attack the United States not from the outside, but from the inside. It was a sign that the United States, the most powerful country in the world, could watch the cathedral of capitalism at the Trade Center and the heart of its defense at the Pentagon be struck internally, not really across borders, so that borders don't matter anymore.

Independence used to be the ticket for liberty. But today, security and freedom, whether it's in the Arab Spring, whether it's in Iraq or whether it's right here in the United States, means working cooperatively and interdependently with others.