The idea of the oikoumene created a paradigm of geography which was based not only on the knowability of the world, but also upon its usability. It relied on theories of limit and transgression. Throughout the sixteenth century the concept of the oikoumene persisted, in that geographers and explorers alike still wrote about the extent of the inhabitable lands, but they began to believe that all landmasses in the world were not only inhabitable but made for humans to exploit. Therefore all the different regions of the earth were made by God to interact with one another. As the chapter argues, in order for a classical geography of limit and transgression to be reimagined as one of connectedness and communication, the frigid and torrid zones which had demarcated the limits of the classical world had to be reconceptualised as inhabitable and knowable places.

The chapter first examines how and why the Greeks and Romans developed the concept of uninhabitable frigid and torrid regions denoting the limits of the oikoumene. In the process it demonstrates why these climatic limits became conceptual margins that hindered exploration for nearly two thousand years. It looks at the reevaluation of authority which still saw the Greeks and Romans as the arbiters of knowledge, but enabled non-canonical classical authors to become important in revising attitudes to the climatic zones which had once been thought to define the edges of the oikoumene. In the new geography, the arctic and equatorial regions were believed to play key roles in allowing the different parts of the world to interact with one another. Without this shift in mind-set about the frigid and torrid zones, it would have been impossible for Europeans to begin to think of the world as a single, exploitable, global unit, created by God for human dominion. The oikoumene could not have become coterminous with the world.

The idea of limit was fundamental to ancient geographical thought, and without exception ancient geographical writers focussed in some way on the idea of boundaries. Both Ptolemy and Strabo, as we have seen, spoke of the oikoumene, a term whose very existence implied a separation of one part of the world from the rest, denoting a region of human inhabitation which did not coincide with the whole world, but was restricted and limited. No classical writer thought that the oikoumene comprised the whole world.