Next comes the earth, that one part of nature that for her many gifts to us
we honour with the name of Mother. She is our realm, as the sky belongs
to the gods. She welcomes us when we are born, nurtures us as we grow,
and when we are adults sustains us always.
(Pliny, Natural History 2.154)
From its foundation to the Arab conquests the story of Rome was played out over a millennium and a half At first expansion was so slow that few outside Italy can have noticed it. But by the reign of Augustus the empire was bounded by the Atlantic to the west and the Sahara to the south, its northern frontier bisected temperate Europe, and its eastern edge was extended deep into western Asia. There the frontiers more or less rested until disintegration began at the end of the fourth century, once again slow at first but eventually collapsing into the Aegean world of seventh-century Byzantium. That fiftygeneration tale of rise and fall is an epic one in human terms.
Geologically, however, a millennium and a half is the blink of an eye. The Roman Empire was a bubble that grew on the surface of the pond and then burst. During this time the physical environment of the Roman world—its landforms and climate in particular—hardly changed. New crops and methods of agriculture spread, but they had only a little impact on the landscapes Rome ruled over. Had Romulus been transported seven centuries forward