text:  Historian Doris Kearns Goodwin is with us now. She has written biographies of numerous U.S. presidents, including Teddy Roosevelt, Abraham Lincoln, and Lyndon B. Johnson. Her latest book is An Unfinished Love Story, A Personal History of the 1960s. Doris Kearns Goodwin, thank you so much for joining us. I'm glad to be with you today, Scott. I want to start with just what you were thinking when you saw what happened Saturday night. I guess what was going through my mind is just what can history help us