Author and historian David McCullough (left) appears in conversation with philanthropist David Rubenstein at the 17th annual Library of Congress National Book Festival at the Walter E. Washington Convention Center in Washington D.C. on Saturday, September 2, 2017. McCullough is a two-time winner of the Pulitzer Prize and the National Book Award and a recipient of the Presidential Medal of Freedom. His newest book is "The American Spirit: Who We Are and What We Stand For." (Photo by Jeff Malet)
