It's official; Senator Barack Obama is now president-elect of the U.S.. He is the first African-American to be elected to the country's highest office. If you want a second opinion on the historic nature of the moment, just feel the crowd's energy (at about 1:40) in the above clip. Of course, no matter how many times you hear a cable news anchor say "historic," or worse "historical" (that word doesn't mean what you think it means, Anderson Cooper!), it begs the question, what do the people who measure history as their life's work, think of this moment? We've got four eminent scholars with us this hour -- Annette Gordon-Reed, Robert Kagan, Victor Davis Hanson, and Bernice Johnson-Reagon -- to give their own, long, view on this American moment. What do you think has changed?