A MUTUAL, JOINT-STOCK WORLD IN ALL MERIDIANS

But on the ground, it is far from clear that these developments constituted a defeat for civilization. Within a decade of the sack of Rome, Alaric's successor was being quoted as saying that in his youth he had thought to overthrow the Roman empire and replace it with a Gothic one, but now in power he saw that his people needed the law and structure of Roman civilization to have peace and prosperity for themselves. All of those "barbarian" kingdoms would soon rewrite the Roman law codes for local use and practice, in eloquent testimony to the power of the greatest of Roman civil achievements.

Roman government persisted in demonizing the barbarian, and the politics of the fifth and sixth centuries persisted in seeing the challenges of the age as military and technological. They could not have known or heard the lesson of a famous line from the modern French poet Paul Valery: "Seeing is forgetting the name of the thing one sees." The Romans of that age knew exactly what they were seeing - and it made them blind to the reality around them.

And so the long dance of Roman armies and barbarian ones played out, and in the end, Rome was the loser. Preoccupation with barbarians took attention away from another more threatening military frontier, the one shared with Persia, and gradually Roman resolve and strength were worn away there. When Islam arose in the seventh century, the remaining Roman power, headquartered at Constantinople (modern Istanbul) was unable to mount more than a token resistance.

But the final irony is important to grasp. You may have visited modern Rome or seen pictures of its ancient ruins, and you may be thinking that the events of 410 of which I spoke earlier can explain what you have seen. Not so.

The greatest destruction visited upon the city of Rome, the depredations that left most of the city a prey to malaria and a home to oxen and owls for a thousand years, came not from barbarian invaders but Roman ones. In the mid-sixth century, the reigning emperor at Constantinople, preoccupied with his vision of barbarism versus civilization, sent his own mercenary army (containing, to be sure, a good many fighters of non Roman stock) to recapture Italy for the empire. The fifteen years of war that followed were responsible for the destruction of much of the physical fabric of Rome, and responsible as well for shattering the political and social unity of the peninsula that had been built up laboriously through many centuries. From the sixth century to the nineteenth, there was no Italy, only a peninsula divided among pieces of other people's property. That disarray was the result not of barbarism, but of self-styled civilization run amok.

Could it have been otherwise? Was there an alternate future in the aftermath of the sack of Rome? Choices in history are hard to see as we live the history, but perhaps a little easier to see from a distance.