This documentary did something great movies (or books) do — force me to reconsider a long-held belief. Since my teens, I've believed in that quote by Martin Luther King, Jr., "The arc of the moral universe is long, but it bends towards justice." After watching "13th" I have to consider the possibility that the arc bends back on itself in an endless cycle of fighting the same old evil. Racism is a disease. Just when we think it's vanquished (13th Amendment, Civil Rights Act, Voting Rights Act), the evil metastasizes and erupts in new form (criminalization of race, mass incarceration). Now, in the early 21st Century, the arc of the moral universe has bent back to its starting point once again.