Because in the faces of those young veterans who come back from Iraq and Afghanistan, I see my grandfather, who signed up after Pearl Harbor, marched in Patton's Army and was rewarded by a grateful nation with the chance to go to college on the GI Bill.

In the face of that young student who sleeps just three hours before working the night shift, I think about my mom, who raised my sister and me on her own while she worked and earned her degree; who once turned to food stamps but was still able to send us to the best schools in the country with the help of student loans and scholarships.

When I listen to another worker tell me that his factory has shut down, I remember all those men and women on the South Side of Chicago who I stood by and fought for two decades ago after the local steel plant closed.

And when I hear a woman talk about the difficulties of starting her own business, I think about my grandmother, who worked her way up from the secretarial pool to middle-management, despite years of being passed over for promotions because she was a woman. She's the one who taught me about hard work. She's the one who put off buying a new car or a new dress for herself so that I could have a better life. She poured everything she had into me. And although she can no longer travel, I know that she's watching tonight, and that tonight is her night as well.

I don't know what kind of lives John McCain thinks that celebrities lead, but this has been mine. These are my heroes. Theirs are the stories that shaped me. And it is on their behalf that I intend to win this election and keep our promise alive as president of the United States.

What is that promise?

It's a promise that says each of us has the freedom to make of our own lives what we will, but that we also have the obligation to treat each other with dignity and respect.

It's a promise that says the market should reward drive and innovation and generate growth, but that businesses should live up to their responsibilities to create American jobs, look out for American workers, and play by the rules of the road.

Ours is a promise that says government cannot solve all our problems, but what it should do is that which we cannot do for ourselves, protect us from harm and provide every child a decent education; keep our water clean and our toys safe; invest in new schools and new roads and new science and technology.

Our government should work for us, not against us. It should help us, not hurt us. It should ensure opportunity, not just for those with the most money and influence, but for every American who's willing to work.

That's the promise of America, the idea that we are responsible for ourselves, but that we also rise or fall as one nation; the fundamental belief that I am my brother's keeper; I am my sister's keeper.