Twenty-one years ago, on the National Mall, Louis Farrakhan rose to speak to the largest gathering of African Americans in history. Flanked by a crowd of young men in navy-blue uniforms, Farrakhan looked out at the Million Man March, a sea of black humanity that stretched from the Capitol to the Washington Monument. The people had gathered at a time of profound suffering for black America. The fire of the civil-rights movement had burned out; the hope and progress of the 1960s had turned to cynicism and regression. The march had been conceived as part of the great legacy…