The news Wednesday morning that Don Cornelius, the iconic host and founder of “Soul Train” — a.k.a. “the hippest trip in America” — had died, apparently by his own hand, at first brought shock and disbelief. Then a sustained round of going back in the day.

Before BET or MTV, before cable television or the Internet, TV’s “Soul Train” taught a generation how to dance and let black America see itself having fun. At the center stood Cornelius in all his preternatural cool.