Today's protesters should remember the lessons of revolutions past, but most of all they should remember the importance of debate, discussion and argument.
Lynchings and racist murders didn't end with the passage of the Civil Rights Act. Even in 2012, people of color can't walk in safety in many parts of the country.
Each of these movements won lasting social change. Their limitations provide lessons about what not to do, while their successes offer a guide to future action.
