The book by Zoe Oldenburg, our compatriot, who left for France as a child and devoted her life to the hard work of a historian, is rightfully considered one of the fundamental works about the Albigensian Crusades and the mysterious phenomenon of the Cathar heresy. The book is written clearly, not harshly in a feminine way, and at the same time is distinguished by that emotional poignancy that does not allow you to read it without deep emotion.