The Cave and the Light: Plato Versus Aristotle, and the Struggle for the Soul of Western Civilization

by Arthur Herman

In any event, Eratosthenes took Pytheas’s book and did some quick calculations based on his own estimate of the earth’s diameter. He concluded that if the Indian Ocean was not a landlocked sea, as most Greeks supposed, but opened up onto a still larger ocean extending to the shores of the Pillars of Hercules, as Pytheas’s voyage indicated, then it might be possible for a sailor to sail west from Spain to India, although Eratosthenes calculated it would take at least thirteen thousand miles.§ Furthermore, he speculated, perhaps there was even another “inhabited world” (oikoumenē) to be found between Spain and India, one that covered at least part of the western hemisphere of the globe—a hemisphere that mathematics proved had to exist since the earth was round, but which was still entirely unknown.18 His Aristotelian colleagues scoffed. How could one predicate the existence of something no one had ever seen, especially an inhabited landmass; and when everyone knew the Indian Ocean ended at the western shores of India? So Eratosthenes’s stunning thesis of a possible New World located between Europe and Asia never caught on, even after the Romans discovered there was indeed an ocean on the far side of India. His idea of a western continent faded from the science books. It would take Columbus’s accidental discovery in 1492 to finally prove that the Aristotelians at Alexandria had been wrong and Eratosthenes right all along.