Studying manuscripts is often an adventure. The starting point is known: it is established by the studies dealing with our subject and sectorial bibliography. Although the point of arrival is well defined in our minds, it may sometimes be embellished through the power of imagination, but it always remains clear, limpid and lucid: it is indeed an academic adventure and the perspective must have a scientific cut. On the contrary, the path is discovered as we go along, it is something else entirely:...