From here on, my attention no longer focuses on the surviving copy of the map but turns to the lost original. This chapter addresses its fundamentals: authorship and date; sources; context and purpose. By their very nature these aspects are interrelated, and any conclusions drawn about them can only be tentative at best in view of the loss of the object itself. But the importance of the questions to be raised justifies the attempt to formulate responses, however imperfect. Taken together, those proposed here envisage the original map as a bold experiment in combining and developing established approaches to cartography. A novel form of map is the result, with the forceful ideology of Diocletian's Tetrarchy (c. A.D. 300) as its principal inspiration.

AUTHORSHIP AND DATE

In antiquity it was rare for products of technical or artistic expertise to carry their maker's name. Thus the absence of any such name on the surviving copy of the map is no surprise, and the likelihood is that none appeared on the original in the first place. The only scholar who has proposed a named individual as the maker of the original is Konrad Miller. He dated it to the late fourth century and attributed it to Castorius. This identification derives from the fact that one Castorius happens to be the source most often cited in a Cosmographia (by an anonymous cleric claiming to be from Ravenna, c. 700) for information likely to be somehow derived from itineraries.