In his Decline and Fall, Gibbon covered more than 1,400 years of history, from 180 to 1590. This was history over the very long run, in which the causes of decline ranged from the personality disorders of individual emperors to the power of the Praetorian Guard and the rise of monotheism. After the death of Marcus Aurelius in 180, civil war became a recurring problem, as aspiring emperors competed for the spoils of supreme power. By the fourth century, barbarian invasions or migrations were well under way and only intensified as the Huns moved west. Meanwhile, the challenge posed by Sassanid Persia to the Eastern Roman Empire was steadily growing. The first time Western civilization crashed, as Gibbon tells the story, it was a very slow burn.

But what if political strife, barbarian migration and imperial rivalry were all just integral features of late antiquity – signs of normality, rather than harbingers of distant doom? Through this lens, Rome’s fall was in fact quite sudden and dramatic. The final breakdown in the Western Roman Empire began in 406, when Germanic invaders poured across the Rhine into Gaul and then Italy. Rome itself was sacked by the Goths in 410. Co-opted by an enfeebled emperor, the Goths then fought the Vandals for control of Spain, but this merely shifted the problem south. Between 429 and 439, Genseric led the Vandals to victory after victory in North Africa, culminating in the fall of Carthage. Rome lost its southern Mediterranean breadbasket and, along with it, a huge source of tax revenue. Roman soldiers were barely able to defeat Attila’s Huns as they swept west from the Balkans. By 452, the Western Roman Empire had lost all of Britain, most of Spain, the richest provinces of North Africa, and south-western and south-eastern Gaul. Not much was left besides Italy. Basiliscus, brother-in-law of Emperor Leo I, tried and failed to recapture Carthage in 468. Byzantium lived on, but the Western Roman Empire was dead. By 476, Rome was the fiefdom of Odoacer, King of the Scirii.99

What is most striking about this more modern reading of history is the speed of the Roman Empire’s collapse. In just five decades, the population of Rome itself fell by three-quarters. Archaeological evidence from the late fifth century – inferior housing, more primitive pottery, fewer coins, smaller cattle – shows that the benign influence of Rome diminished rapidly in the rest of Western Europe. What one historian has called ‘the end of civilization’ came within the span of a single generation.100

Could our own version of Western civilization collapse with equal suddenness? It is, admittedly, an old fear that began haunting British intellectuals from Chesterton to Shaw more than a century ago.101 Today, however, the fear may be better grounded. A large majority of scientists subscribe to the view that, especially as China and other big Asian as well as South American countries narrow the economic gap between the West and the Rest, humanity is running the risk of catastrophic climate change. Without question there has been an unprecedented increase in the amount of carbon dioxide in the earth’s atmosphere. And there is some evidence that this has caused an increase in average temperatures. What is less clear is how a continuation of these trends will impact on the earth’s weather. However, it does not seem entirely fanciful to imagine further melting of the polar icecaps leading to changes in the direction of ocean currents or flooding of low-lying coastal regions; or the further desertification of areas hitherto capable of sustaining agriculture. Quite apart from climate change, some environmentalists also fear that, as Asia’s more populous nations follow the Western route out of poverty, the strain on global supplies of energy, food and fresh water will become unbearable. Sceptics about the risks of climate change should spend some time in China, where the biggest and fastest industrial revolution in history is causing measurable – indeed, unmissable – environmental damage.

Most people who discuss these issues – myself among them – are not scientifically qualified to weigh the evidence. What attracts us to the idea of an environmental disaster is not so much the data as the familiarity of the prediction. Since the earliest recorded myths and legends, mankind has been fascinated by the idea of a spectacular end of the world, from the ‘twilight of the gods’ in the Nibelung saga to the key text of Christian eschatology, the Book of Revelation, written by the Evangelist John of Patmos. In this version of the apocalypse, the Messiah or Lamb of God will return to earth and defeat the Antichrist in the Battle of Armageddon, after which Satan will be confined to a bottomless pit for a thousand years. The culmination will come when Satan re-emerges from the abyss and summons together the people of Gog and Magog. This will be the cue for ‘voices, and thunders, and lightnings; and … a great earthquake, such as was not since men were upon the earth’ (Revelation 16:18). Jehovah’s Witnesses and Seventh-Day Adventists both subscribe to a literal interpretation of this prophecy, but they are by no means alone. A remarkably large number of Evangelical Christians in the United States say they share the belief that we are nearing the End of Days. For many, the only question is who will be left behind when the ‘Rapture’ comes. Some say the phase of tribulation has already started. On 14 December 2008, it is said, the First Trumpet sounded, as the financial crisis neared its nadir. Once the Second, Third and Fourth Trumpets have sounded, the United States will collapse as a world power. When the Fifth Trumpet sounds, the Third World War will break out, killing billions of people. Then, on the last day of this great tribulation, Jesus Christ will return to redeem the true believers, as foreseen in the Book of Revelation. On a trip to the barren hill at Megiddo in Israel, commonly held to be the site of the coming Battle of Armageddon, I was not wholly surprised to encounter a party of Americans drawn there by precisely this kind of millenarian belief. Like those unreconstructed Marxists who continue to yearn for the collapse of capitalism, interpreting each new financial crisis as the beginning of the end, they feel a certain frisson at the thought that the End might come on their watch.

This idea that we are doomed – that decline and fall are inevitable, that things can only get worse – is deeply connected with our own sense of mortality. Because as individuals we are bound to degenerate, so, we instinctively feel, must the civilizations in which we live. All flesh is grass. In the same way, all vainglorious monuments end up as ruins. The wind blows through the melancholy relics of our former achievements.

But what we struggle to decide is how exactly this process of decline and fall unfolds in the realm of complex social and political structures. Do civilizations collapse with a bang, on the battlefield of Armageddon, or with a long, lingering whimper? The only way to answer that concluding question is to return to the first principles of historical explanation itself.

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