It is one of William Faulkner’s most quoted lines. “The past is never dead,” he wrote in his novel Requiem for a Nun. “It’s not even past.” In fact, it’s being rewritten all the time for contemporary contexts. But when college students try to erase whole parts of the historical record, as many seem to want to do these days, it’s time to point out the lessons history has to offer about the consequences of such behavior—and how easily zealous righteousness is transformed into tyranny.