Yves Congar, a key theologian in Vatican II, especially regarding the Council's ecclesiology, writes:
"A Christian of the Fourth or Fifth Century would have felt less bewildered by the forms of piety current in the Eleventh Century than would his counterpart of the Eleventh Century in the forms of the Twelfth. The great break occurred in the transition period from the one to the other century. This change took place only in the West where, sometime between the end of the Eleventh and the end of the Twelfth Century, everything was somehow transformed. THIS PROFOUND ALTERATION OF VIEW DID NOT TAKE PLACE IN THE EAST where, in some respects, Christian matters are still today what they were then and what they were in the West before the end of the Eleventh Century."
- After Nine Hundred Years by Yves Congar