In 798, Charlemagne wanted to build a monastery in Jerusalem, which was then under the nominal rule of the Caliph Haroun al-Rashid. So Charlemagne sent an embassy to Baghdad, led by one Isaac the Jew. After four years Isaac returned, bringing a fabulous present from the Caliph - an elephant called Abulabaz.
With the elephant came building permission for the Jerusalem project, and a Benedictine community was ordered to establish a monastery. They appear to have been a very up-to-date crowd, getting into the ninth century well ahead of everyone else. Not only did they sing the Creed in the Mass, but used the controversial 'filioque' clause - asserting that the Holy Spirit proceeds from the Father and the Son, and not simply from the Father. But the Greek Christians of Jerusalem had spent a century and a half maintaining the older form of the Creed in the face of Muslim dominance, and were outraged. The rest, as they say, is history, with Christendom splitting asunder in 1054. The elephant died on campaign in Saxony in 810. His tusks were made into chess pieces, some of which still survive. He is buried in Aachen, the Frankish imperial capital.
This little tale is told by Judith Herrin in her remarkable book The Formation of Christendom. She uses the story to illustrate her case that the European, Mediterranean culture of Christendom was a product of interaction between Catholic, Orthodox and Muslim, and indeed of the conflict between them. This seems at first sight an interesting notion, a plot line Mary Renault could have used, but redundant in a world made new by Columbus and Lenin. Except that the Atlantic has got so much wider in recent years, and Lenin now seems as historically remote as Abulabaz.
We certainly see the old order of Catholic, Orthodox and Muslim savagely on display in what we once more call the Balkans. But this is not simply an isolated instance. The collapse of Leninist rule has signalled a big comeback for the anciens regimes. Muscovy is back with us, and Cathay seems on the way. Indeed, Europe is beginning to look as it might have done had the Thirty Years War been over by Christmas. It is said that Otto von Habsburg is not just sitting in the European Parliament - he is waiting.
It all seemed unlikely in the ages of simple faith - faith, that is, in the secular ideologies which once swept the world. Take the 1860s. With Bismarck, Garibaldi and the rest running amok, Pius IX produced the deathless phrase to describe their brave new world - 'Civilisation as recently invented'. There seems hardly a better way effectively to resign from the modern world.
But over the past half century something odd has happened - Catholic lay politics has moulded modern Europe as much as it has itself been changed. The politics of Christian Democracy have also shaped official Catholic social teaching somewhat. If you go to Germany with Centesimus Annus in hand, you seem to have got a map of the place - just the same careful balance of competition and co-operation, rights and obligations.
Looking at what seems to be our common European model of political economy, the idea suggests itself - the European settlement is a Catholic settlement. Hardly suprising on reflection, when those who said most emphatically after the last war 'never again' were convinced Catholic laymen - Jean Monnet, Robert Schuman, Alcide de Gasperi, Konrad Adenauer.
And, astonishingly, quasi-Catholic Europe has recognisably the same neighbours as in Charlemagne's day - the Muslims of North Africa and Turkey, and the lands of Orthodoxy, now stretching away to Vladivostok.
For both these communities the European settlement still looks rather like 'civilisation as recently invented'. The fact that neither of them has reached a settlement remotely like the European one is certainly unnerving, and is likely to loom large in the next century. But Judith Herrin's point is that we always were different, and it looks as if we shall have to endure that difference for some time to come.
Our Mediterranean Europe has at least four main characters, however - Isaac the Jew is, after all, rather central to the story of Haroun al-Rashid's elephant. And the Israeli settlement is something like the European one - to the scandal of Israel's neighbours. It is also perturbing how much the Balkan horrors resemble Europe's past, including its anti-Semitic past. It remains to be seen how these four characters cope with the coming century, without Lenin to blame if they make a mess of it.
But there's always the strong sense that the future lies to the north and west - that nobody gets it right till they have been through the Renaissance and the Enlightenment, the Eton and Oxford of European belonging. And yes, it is true, from these experiences there sprang great wells of imagination and human sympathy. But where, apart from a rather fraying altruism, is this superiority clearly evident - and, such as it is, will it survive a serious faltering in economic growth?
The tragedy of the last 1,000 years is that our communities thought they had nothing to learn from one another. The irony is that each has actually been thoroughly shaped by the others. If we do not understand this, we are likely to blunder through the coming centuries in much the same fashion as the last few. There is here what might be called the Paradox of Haroun al-Rashid's Elephant - that things change terrifyingly fast from one year to the next; but not very much over a millennium.