Predicting the future usually means extrapolating today’s fashions into long-term trends. In the early 1970s I read an article prophesying that by the year 2000 (now!) there would be no more broccoli. The idea was that since frozen and powdered foods, the latest innovations in their field, had captured much of the market, fresh produce would soon disappear, except maybe for those those cube-shaped, agribusiness-developed tomatoes that were supposed to be on their way in.

Of course the author didn’t foresee Dean & Deluca: that just twenty-five years later, humble low-tech vegetables, preferably dirt-farm organic and with names you’ve never heard of, like burdock root, would play a key role as turn-of-the-millennium status symbols, the consumption of which would separate snobs from slobs at high-end restaurants and upscale grocery chains. The giant food-processing megacorporations would turn out to have the problems, currently consolidating hurriedly in the face of static customer bases.

The lesson: whether you are a Long Boom optimist or a long-gloom pessimist, palm-reading the lifestyles of the future usually sets you up to be proved wrong. Right now the Silicon Valley is hot, so futurists are preaching that the next thousand years are going to be just like the Silicon Valley, only without the traffic and without disease, war, poverty, or death. Maybe”but don’t count on it. “Life is a great surprise,” wrote Vladimir Nabokov, and that goes for the next five years as well as the next five hundred.

It is possible, however, to make some very general predictions about the next millennium, not by projecting the fads of the present but by studying the patterns of the past. That is because those who do not understand history are condemned to repeat it, and hardly anyone understands history. One way to imagine what the long-term future will bring is to examine what one could have imagined the future would bring if one were living at the beginning of the second millennium in the year 1000, or the first millennium in the year One.

Let us look at the earlier period first. Two thousand years ago, most of the Western world lived under the political and cultural hegemony of a “lone remaining superpower” known as Rome. Over the preceding several centuries this upstart Italian city had extended its civic borders to encircle the Mediterranean and had demolished and absorbed the Hellenistic empire that Alexander the Great had cobbled together. Superbly trained and equipped Roman legions stationed everywhere ensured peace (except for border skirmishes) and allowed a mari time shipping trade to flourish on a scale that would not be surpassed until the nineteenth century. To its colonies, Rome offered a universal rule of law, a universal language (Latin), and the possibility of universal citizenship even for the foreign-born. The Romans did not have the microprocessor, but they did have a kind of functional equivalent: slaves, whose labors underlay the creation of immense wealth. Catering to the new prosperous class, Virgil, Horace, Ovid, and Livy turned out epic and lyric poetry and elegant prose to rival the finest literature of the Greeks.

The Roman Empire seemed destined to last forever. However, a shrewd observer of the first-century scene, perhaps a Roman general posted in Pannonia or Syria, might have noticed the beginnings of massive changes that would sweep away the entire edifice over the next few centuries. Those changes were not political but cultural and demographic. Our general would probably have not have noticed the harbinger of the most significant change of all: the little Jewish boy playing with wood-shavings in the obscure hamlet of Nazareth. A few decades later, though, he might have observed with alarm, as the emperor Nero certainly did, that increasing numbers of people, even in Rome, were worshiping this Jew as a god (and refusing to worship the emperor, or to respect the empire beyond a point), even though the supposed god had been executed as a felon after full and fair Roman justice.

Our sharp-eyed general would have noticed other things: that the Latin language, for example, although widespread and official, was in slow decline. Already in the early first century, the best years of classical Latin literature were over, and by the middle of the second century the empire’s finest thinkers and stylists would be writing in Greek: Plutarch, Galen, the satirist Lucian. Even Marcus Aurelius, Edward Gibbon’s ideal noble Roman, used Greek for his Meditations . Among the unlettered, spoken Latin was either dying out or imploding into the Romance languages.

There were also ever fewer Romans, culturally speaking. As early as Jesus’ time, the imperial city was recruiting many of its fighting men from Asia, and they brought their customs and gods with them into Europe. Gradually, the empire’s center of gravity moved geographically and ethnically eastward. By the time of the emperor Decius in the mid-third century, the imperial throne itself was a preserve of ethnic Balkans, and not long after that, the emperor Diocletian split the empire into east and west. Most tellingly of all, Rome never managed to extend its northeastern frontier much beyond the Danube, and it spent some five hundred years waging defensive warfare against the increasingly numerous German tribesmen on the other side. Our prescient Roman general might have foreseen that eventually his government would lose its fighting energy, and that the descendants of Julius Caesar’s harriers would pour into every corner of Western Europe, pushed by even more aggressive nomads from farther east.

By the year 1000, the beginning of our own millennium, there was still an entity that called itself the “Roman Empire.” There were two such entities, in fact: a glittering, polyglot theocracy on the Sea of Marmara, and a loosely organized Frankish kingdom in Northern Europe. Neither bore much resemblance to the Rome of old. In contrast to the confident imperial mood at the beginning of the first millennium, the mood at the beginning of the second millennium was generally one of exhaustion. Christianity itself seemed tired, its monasteries fat but spiritually moribund, its prelates beholden to secular rulers, and its eastern and western flanks so embittered by their cultural differences that in 1054 they acrimoniously split apart. The populations, economies, and cities of Western Europe were shadows of their former selves, beaten down by centuries of invasions, most recently from the most belligerent of the Germans, the Vikings. Some thought the world was about to end.

And yet, during the very year 1000, something happened that turned out to set the course of the entire millennium in a new direction: one of the Vikings, Leif Ericsson, who had decided to convert to Christianity a few months before, discovered America. Fifty years later, Leif’s distant kinsman Thorfinn, the last of the Norse pirate chiefs, retired his longboat and made a pilgrimage to Rome; that was the end of Viking raids.

In the year 1016, the Benedictine abbey at Cluny in France declared itself independent of outside supervision and spearheaded a rolling reform of the monasteries that swept through Europe. Cluniac monks in turn supported Pope Gregory VII’s singleminded and ultimately successful efforts to free the Church from secular control later in the century (see Robert Louis Wilken, “Gregory VII and the Politics of the Spirit,” FT, January 1999). The monasteries had always been centers of learning, and they now became powerhouses of creative invention. Such medieval innovations as the horse-drawn plow and the water mill (which greatly enhanced farm productivity), the glass lens, the clock, the flying buttress, and double-entry bookkeeping marked the beginnings of the long wave of technological, scientific, and commercial development that, for good or ill, is the very signature of the second millennium in the West.

A very prescient monk at Cluny in the year 1000 would not have foreseen exactly how things would turn out today”he could not have predicted the Internet”but he might well have suspected that the renewed spiritual energy at his own monastery would flow infectiously outward. In fact, the eleventh century proved to be one of the West’s most energetic; it was the time of El Cid, the earliest Crusades, the Norman Conquest, and the beginning of a new synthesis of classical and Germanic civilizations.

All this says something about what it may be like in the year 3000, if the Last Days don’t overtake us first. Our own country, like Rome, is the richest and most powerful on earth, but it is also in the throes of sweeping demographic changes, as Rome was at the beginning of the first millennium. America’s language, English, is in universal use, but it is also in a state of grammatical decomposition and literary decline. A thousand years from now, there may still be an entity that calls itself “the United States,” just as there was a Rome in the year 1000, but don’t expect it to be much like today’s U.S.A. At the same time, there is currently a crisis of cultural self-confidence in the West that resembles the malaise of a thousand years ago. The combination of new people (waves of immigrants from south and east) and a fading sense of common values seems to spell disaster, and there will undoubtedly be upheavals aplenty in the future as there have been in the past.

But if history teaches us anything, a vibrant new civilizational synthesis may also be just around the corner. Furthermore, we can take comfort from the things that have survived for 2,000 years and are likely still to be around when another thousand have passed: wine and song; dogs and ball games; parties and horoscopes; sandals and earrings; the Greek and Latin classics; lovely young ladies and obnoxious aunts; courage and hope and fear of death; the love of parents for their children.

And faith. As the third millennium begins we seem to be on the verge of a great religious revival, and we should remember that it was a new spiritual beginning that set in motion those momentous changes the last two times around.

Charlotte Allen is the author of The Human Christ: The Search for the Historical Jesus (Free Press) .