Two unlikely tourists traveled through the Hudson Valley and New England in the early summer of 1791, wanting to study the region's flora and fauna as well as the Native American languages. Or were Thomas Jefferson and James Madison on a political mission? We talk with Louis P. Masur, cultural historian, who has written books about Benjamin Franklin, Abraham Lincoln, photography, baseball, and rock and roll, and is now writing a book about Jefferson and Madison's exploration of this distant country, where they are looking for the Hessian Fly, become enraptured with sugar maples, meet with Native Americans, and meet Prince Taylor, a free African-American farming near Fort George. Masur, the Board of Governors Professor and Distinguished Professor of American Studies and History at Rutgers University, unpacks the world from a grain of sand, and this encounter with Jefferson and Madison in the summer of 1791 tells us much about the remarkable friendship of these two men and the country they helped to bring into being.