Katie Couric's Notebook: Richard Holbrooke

America has lost one of its most distinguished diplomats, and I've lost a good friend.

Richard Holbrooke is best known for hammering out the 1995 Dayton peace accords that ended the war in Bosnia.

But he never rested on those laurels. He was passionate about everything he worked on.

I remember meeting with him four years ago, when he urged me to cover a story the American media were neglecting: Afghanistan, a country about which he cared deeply.

He was known as a tough negotiator, but he was soft-hearted in person. He always wanted to know how the people in his life were doing - if they were happy and if he could help.

At the State Department last Friday, he suffered a torn aorta. As he was taken to surgery, his last words to his Pakistani doctor were "you've got to stop this war in Afghanistan."

Richard Holbrooke was a man who believed that anything was possible, right up until the very end.

That's a page from my notebook.

I'm Katie Couric, CBS News.