Theoretical Aspects. While mathematical astronomy was mostly a matter for Greeks writing in Greek, the Romans were more receptive to geography. As the Romans extended their domain, they were curious about foreign lands, peoples, and cultures. In the second century B.C.E. Polybius, who visited and entertained the Romans with learned discourse, stressed geography as an aid to understanding politics and history. Even more to the point, the ever-expanding empire called for knowledge of the world beyond the borders of Roman control. Although the Romans' contributions to geography were considerable when it came to places, peoples, and distances, nonetheless, the Greeks continued to provide the theoretical aspects. Nowhere can this case be more clearly seen than in the contrast between Eratosthenes (whose brilliant method resulted is a fairly accurate calculation of the circumference of the earth) and Marcus Agrippa. Eratosthenes wanted to...