Abstract
Two cathedrals burned at the same time on April 15 2019 : the one founded in 1163 by Bishop Maurice de Sully, and the one that has been constantly reconstructed by the imagination since the 18th century. In a well-known archaeological paradox, destruction can be the prerequisite for knowledge: the scientific work that accompanies the restoration of the building thus has a revelatory effect on little-known medieval structures -, which is why the very concept of "identical restoration" is so pointless. These structures are archaeological, but they are also cultural, political and social. This is why the "cathedral of knowledge" that we have uncovered is also the one that our contemporary imaginations are building and reconstructing. By saving the past, we can measure its thickness - thatis, everything that happened between the Middle Ages and the present day.
