To peer into the lives of American presidents at their retreats is to see each man as he really was and what emerges is a series of portraits of real human beings, subject to self-doubt and overconfidence, physical afflictions and exhaustion, sorrow and heartache, self-indulgence and lazinessin short, the very same weaknesses and problems that affect the rest of us. Kenneth T. Walsh, chief White House correspondent for U.S.News, takes a look at the private worlds of presidents in his new book, From Mount Vernon to Crawford: A History of the Presidents and Their Retreats.