I have the distinct honor today of pinch-hitting for one of my personal heroes and a hero to this country, Senator Edward Kennedy. Ted is at home, getting some much-needed and deserved rest. And we're so pleased to see many of his family here today, including his wonderful wife, Vicky. He called me up a few days ago and I said that I'd be happy to be his stand-in, even if there was no way that I could fill his shoes.

I did, however, get the chance to glance at the speech he planned on delivering today, and I'd like to start by passing along a message from Ted: "To all those praying for my return to good health, I offer my heartfelt thanks. And to any who'd rather have a different result, I say, don't get your hopes up just yet!"

So we know that Teddy's legendary sense of humor is as strong as ever, and I have no doubt that his equally legendary fighting spirit will carry him through this latest challenge. He is our friend, he is our champion, and we hope and pray for his return to good health.

Now, the topic of his speech today was common for a commencement, and we heard some of the themes from President Roth but one that nobody could discuss with more authority or more inspiration than Ted Kennedy. And that is the topic of service to one's country - a cause that is synonymous with his family's name and legacy.

I was born the year that his brother John called a generation of Americans to ask their country what they could do. And I came of age at a time when they did it. They were the Peace Corps volunteers who won a generation of goodwill towards America at a time when America's ideals were challenged. They were the teenagers and college students, not much older than you, who watched the Civil Rights Movement unfold on their television sets; who saw the dogs and the fire hoses and the footage of marchers being beaten within an inch of their lives; who knew it was probably smarter and safer to stay home, but decided to get on those buses and get in their cars and get on those trains anyway, and take those Freedom Rides down south - who still decided to march. And because they did, they changed the world.

I bring this up today, because you are about to enter a world that makes it easy to get caught up in the notion that there are actually two different stories at work in our lives.

The first is the story of our everyday cares and concerns - the responsibilities we have to our jobs and our families - the bustle and busyness of what happens in our lives. And the second is the story of what happens in the life of our country - of what happens in the wider world. It's the story you see when you catch a glimpse of the day's headlines or turn on the news at night - a story of big challenges like war and recession; hunger and climate change; injustice and inequality. It's a story that sometimes can seem separate and distant from our own - a destiny to be shaped by forces beyond our control.

And yet, the history of this nation tells us that it isn't so. It tells us that we are a people whose destiny has never been written for us, but by us - by generations of men and women, young and old, who have always believed that their story and the American story are not separate, but shared. And for more than two centuries, they have served this country in ways that have forever enriched both.

I say this to you as someone who couldn't be standing here if it were not for the service of others, and wouldn't be standing here today if not for the purpose that service gave my own life.

You see, I spent much of my childhood adrift. My father left my mother and me when I was two. When my mother remarried, I lived overseas for a time, but was mostly raised in Hawaii by her and my grandparents from Kansas. My teenage years were filled with more than the usual dose of teenage rebellion, and I'll admit that I didn't always take myself or my studies very seriously. I realize that none of you can probably relate to this, overachievers that you are, but there were many times when I wasn't sure where I was going, or what I was going to do with my life.

But during my first two years of college, perhaps because the values my mother had taught me - values of hard work, honesty, empathy and compassion - finally resurfaced after a long hibernation; or perhaps because of the example of wonderful teachers and lasting friends, I began to notice a world beyond myself. I became active in the movement to oppose the apartheid regime of South Africa. I began following the debates in this country about poverty and health care. So that by the time I graduated from college, I was possessed with this crazy idea - that I was going to work at a grassroots level to bring about change.

I wrote letters to every organization in the country I could think of. And one day, a small group of churches on the South Side of Chicago offered me a job to come work as a community organizer in neighborhoods that had been devastated by the closing of steel mills. My mother and my grandparents, liberal minded though they were, wanted me to go to law school. My friends were applying to jobs on Wall Street. Meanwhile, this organization offered me $12,000 a year plus $2,000 for an old, beat-up car.

And I said yes. I said yes.

I didn