根据以下资料，回答以下题。 　　Of all Barry H．Landau's anecdotes about his friendships with presidential dogs, perhaps the best is the one about the time the Clinton White House called to postpone his play-date with Buddy．
　　Yes, Landau is both human and an adult, a 60-year-old author, presidential historian, former White House protocol officer and memorabilia collector．But so enamored is he of dogs, and so well connected to a succession of presidents, that he had an appointment for a South Lawn romp one day with Buddy, Bill Clinton's Labrador retriever (拉布拉多犬) .
　　Logistics got in the way, though, and hence Clinton secretary Betty Currie's apologetic voice mail left at the Smithsonian Institution, where Landau was doing research: "I'm sorry, but we'll have to reschedule Mr．Landau's play-date with Buddy."
　　Not surprisingly, this is a happy week for Landau, with the new Obama family dog, Bo, joining a White House tradition that dates to George Washington．It's one that Landau feels is invaluable to a presidency.
　　"Having a dog just humanizes a president," he says．"It completes the picture．It's something people can relate to."
And Landau has related to the best of them．He's known about 25 White House dogs since the Eisenhower administration．Among the presidential-pooch memorabilia in his Manhattan apartment are matching orange inaugural dog coats worn by LBJ's twin beagles (小猎犬) , Him and Her, and a photo of Landau kissing Clipper, JFK's German shepherd.