It's a sign of progress that we tend to forget how extraordinary tonight's debate will be, but Walter Dellinger--who taught law at Ole Miss in the late 60s--offers a well wrought reminder in Slate:
Somewhere in my attic there is a fading copy of a campus newspaper from 1967—my first year as a law professor at the University of Mississippi. The headline, as I recall, says "Negro to Address Ole Miss Class." In the space of my own adulthood, a world in which a guest lecture by a black man was a front-page news story has morphed into a world in which a person of color will be speaking on the Rebel campus tonight as a candidate for president of the United States.
As they say, read the whole thing.