“We have to have a special care for the problems of the Muslim world,” Clinton said. “We have to help people help themselves.”

But Clinton said with a more open global society, there are greater threats, some of which may not be overcome simply through greater understanding.

“We live in a world without walls,” Clinton said. “We will have to defeat those who want to tear it down.”

Clinton was often animated during his speech, reeling off statistics and facts in rapid succession, while using trademark hand gestures to emphasize points.

But the speech was not all serious—after Clinton spoke, Summers introduced Harvard football team captain Ryan M. Fitzgerald ’02, who presented Clinton with a football from Saturday’s victory over Yale in The Game, as well as a Harvard football jersey with Clinton’s name.

Clinton playfully tossed the ball to Summers, who bobbled and dropped it, before picking it up and tossing it back to Clinton.

Clinton also took a dig at President George W. Bush’s recent tax cut, joking that the Clinton administration should have protected money in the same way Harvard does.

“If we had called it an endowment, that tax cut never would have passed, and we’d be on our way to a debt-free America,” Clinton said, drawing cheers from the crowd.

After the speech, Clinton headed to the Institute of Politics ARCO Forum, where he participated in an hour-long question-and-answer session, covering topics ranging from the Middle East peace process, restrictions on civil liberties and education funding in developing countries.

Clinton went on to dine with President Summers.

—Staff writer Lauren R. Dorgan contributed to the reporting of this article.

—Staff writer Imtiyaz H. Delawala can be reached at delawala@fas.harvard.edu.