" Even if we admit that running-survey and compass techniques somehow being used on ships to produce sea-charts as early as the thirteenth century (which most historians of science would rule out) we still come against the unexplained enigma of the miraculous and fully formed appearance of the . As we've seen, not a single chart pre-dates it that demonstrates in any way the gradual build-up of coastal profiles across the whole extent of the Mediterranean that have occurred before a likeness as perfect as this could have been resolved. It is possible, of course, through the vicissitudes of history, that all the evidence for the prior evolution of portolans before the has simply been lost. If that were the case, however -- in other words if the is a snapshot of a certain moment in the development of an evolving genre of maps, and if we accept that all earlier 'snap-shots' have been lost, wouldn't we nevertheless expect that such an 'evolving genre' would have to evolve after the date of the earliest surviving example? Whether we set the date of the between 1270 and 1290 [...] or a little later -- between 1295 and 1300 -- as other scholars have argued, we've seen that there was . Now kept in the Bibliothèque Nationale in Paris, the enigmatic is an unsigned chart and scholars have no idea who the cartographer might have been. "