Mediterranean islands in Ptolemy's Geography: Mapping seas through geometrization

The Geography of Claudius Ptolemy is the sole work of ancient geography that presents an easily recognizable and rather realistic depiction of the Mediterranean Sea. The article ultimately aims to explain how Ptolemy achieved such results, given the available sources and methods of his time. It explores how Ptolemy structured the space of the Mediterranean Sea, examining how he positioned the major islands (Sicily, Sardinia, Corsica, Crete, Euboea, Rhodes) and two peninsulas (the Southern Balkans and the Crimea). It is argued that Ptolemy's outlines of the Mediterranean Sea can be accounted for as a result of using three theoretical tools available in his time for map construction: the so-called klimata or reference parallels, the wind rose for determining directions, and the so-called ‘opposite places’ or coastal points presumably situated on the same meridians. The overall outlines of Ptolemy's Mediterranean, and the position of Sicily in particular, are shaped by several latitudes established by earlier geographers. Two regions of Ptolemy's map, in the western and eastern parts of the Mediterranean Sea, are clearly structured based on the 12-point Timosthenes' wind rose, centered at Ostia and Rhodes, respectively. The position of Crete is found to be linked to the African coast by means of the ‘opposite places’ concept. In several cases, the outlines of Ptolemy's map distinctly correspond and can even serve as illustrations to the relevant descriptions found in Strabo's Geography.