The plane loaned to Clinton for this trip is like a flying executive suite. There are framed prints on the walls, high-varnish tables simulating dark wood of the kind you find in boardrooms, and large-screen DVD players. But the plane's real luxury is measured in its gradation of privacy: none in the press and Secret Service section, more for the staff and guests, and perfect seclusion for Clinton. A plate of samosas reveals its other luxury: On a trip like this, meals must be hunted and gathered according to the vagaries of Clinton's schedule. I am impressed by the way the old hands plunder the offered trays of fruit and appetizers and demolish the chicken curry and excellent local ice cream as soon as the dishes appear. Later, I understand that I'm not witnessing greed but grateful opportunity.

Clinton, finally, is on the plane. "Welcome," he says, picking up a samosa as he passes through to his private quarters.

The precise landing time is entered into a log by a Secret Service agent, and the staff rush onto the tarmac. Even in the deserted, late-night Chennai airport, the president's attendants run, and I run with them. I'm reminded of the saises, the extraordinarily fit, fleet runners who preceded the vehicles of the powerful in nineteenth-century Cairo, their speed not only announcing a notable's approach but serving as a symbol of his power to marshal strength and lives not his own—and above all to govern time itself, calendar and clock, the supreme attribute of rulership. This is why months are named for Caesars: These young Americans are enacting an ancient trope of power.

The concerns of the Clinton Foundation, which now employs some seven hundred paid and volunteer workers around the world, are dazzlingly broad: the fight against AIDS; climate change (with a focus on forty of the largest cities around the world); and development projects in Rwanda and Malawi that aim, Clinton says, to create "a proven, comprehensive model for helping people work themselves out of poverty." In the United States, the foundation focuses on urban enterprise in economically depressed areas and on childhood obesity. Then there is the Clinton Global Initiative (CGI), founded in 2005 and described by Clinton as "an inside job" cooked up in consultation with one of his staff. Through CGI, Clinton functions as a kind of cheerleader to a high-powered collection of wealthy individuals, foundations, NGOs, and political leaders and thinkers. Aspiring philanthropists pay a fifteen-thousand-dollar annual membership fee, which allows them to attend the September conference in New York City—the meeting this month will be CGI's third—and make commitments to a diverse, worldwide range of philanthropic projects. Clinton says the September convocation is somewhat modeled on the yearly economic summit in Davos, Switzerland, but its style seems much more drawn from the evangelical "crusades" he loved as a boy: Sinners come up on stage, surrounded by clapping and singing, then bear witness, and at some point cash. Contributors such as Sir Richard Branson may not realize it, basking in that ecstatic applause, but when they come forward, check in hand, it is as Nina Simone said before performing the gospel song "Children, Go Where I Send You": "Y'all ever been to a revival meeting? You don't know what I'm talking about, do ya?…Well, you in one now."