This book   is worth learning French to read: 

   The author cites again and again the terror created deliberately by the papal and civil authorities as they traversed LangD’Oc, and the unrelenting pressure for over a century.

Much more than just the sad burning of nice people (and This is why Each Person needs to Write a Book…):

1. The wiping out of a different culture (use of Roman Law), language, and religion
2. The conquest of an entire cultural region by the north (the ‘French’ annexing what was Provence and destroying the links between Provence and Catalunya-Aragon)
3. The creation of an Inquisition that served as the model for the Spanish Inquisition.
4. Innocent III -> Spanish Inquisition -> los Conquistadores -> Daech: All systematically destroying the writings (or Quipus and museums), languages and history; in short, the cultural memories, that came before them in order…