Medieval people were superstitious about cats, sure, but they were not dumb enough to get rid of them all - ever since agricultural civilisations started making giant piles of rodent food, we have needed them around. (Not to mention the many endearing qualities they have when they are not messing up your important manuscripts.)

Meanwhile, I laughed so hard I had a coughing fit the first time someone told me Dan Brown wrote about the Cathars being the protectors of the secret bloodline of Jesus Christ. THE CATHARS!!! The people who thought it was wrong for anyone/i> to have children because Satan made the material world!