This sin will haunt humanity to the end of time.

It haunts me now.

And I want it to be so.

When he said I want to be haunted by this, he never wanted to forget what he had seen, what he had tried to accomplish, and what from his perspective, he had failed to do.

It's a powerful idea to want to be haunted by something and to make that choice.

And it took Karski, I think, a while to say that.

He said it in 1981.

He thought that he had written two pretty good books.

Karski's memoir, "Story of a Secret State," which he wrote, you know, before the war ended.

That was a book of the Month Club, a bestseller.

But what he really had done was teach a great many students who would never forget him.

For years, Jan Karski's students at Georgetown University knew he was a great professor.

What they didn't realize was he was also a hero.