The other day, I was trying to persuade a political friend of the urgency of doing something to save Palmyra. To be fair to him he understood the horror of what could happen in the next few days. My friend had never been to the ancient city, so I tried to evoke the glory of the colonnades, the temples, the sculptures.I explained the sense of wonder that fills the visitor as you watch the dawn break on the vast fields of rosy old masonry, the amazement at coming far into the deserts of Arabia and finding structures that derive so plainly from ancient Greece and Rome.I think I got across my almost-physical sickness at the idea of surrendering this urban masterpiece to the monsters of Islamic State. I told him of my terror of the sledgehammers and the dynamite of these moronic iconoclasts, and I think he understood where I was coming from. But he gently posed the obvious question: Why Palmyra? Why now? After all, we in the West have done very little to help hundreds of thousands of Syrians. How could I justify an intervention on behalf of inanimate objects?There is no easy rejoinder. The saving of human life should always come first. Nor is Islamic State unique in performing acts of awful cultural destruction: think of Dresden.No nation is entirely guiltless of such crimes. Yet I want to convince you today that there would be something peculiarly catastrophic about the loss of Palmyra. It is not simply an ancient structure that is at stake but what Western civilisation stands for.The more you learn about the Palmyrenes, the more modern they seem to be.For centuries, the city was a great crossroads. Everybody went there and gabbled in Amorite, Aramaic, Arabic, Hebrew, Greek and Latin.They had Roman baths and Greek theatres, and they mummified their dead in the fashion of the Egyptians. They had all sorts of government - Oriental kings, Greek archons and Roman senators, sometimes at the same time. In so far as the Romans were, for a long time, the dominant power, they encouraged local diversity, especially in religion and the worship of all types of Mesopotamian divinities.Of course, there were changes over the thousands of years: one type of temple gave way to another, and the temples became churches, and the churches became mosques. But never in its history has Palmyra faced a threat as brutal as today.Every conquering army, every general that has ever gone there has found something to admire.Not IS - these maniacs cannot cope with the idea of a great culture that predates Islam. They are so pathetic, so troubled, so fearful, so small, that they are driven to destroy - because they apparently cannot stand beauty or representations of the human form. S ome are seemingly the kind of self-hating homosexuals who throw gays off cliffs.This is not Islamophobia, for IS is a complete betrayal of the legacy of great medieval Muslim scholars like Avicenna and Averroes.The behaviour of these extremists is an abomination to all of us, Muslims and non-Muslims alike .One day, Syria will return to some kind of peace. What hope for the Syrian economy, what hope for the tourist industry, if we allow them to smash Palmyra? Even if we had the time and the money, we could not hope to rebuild the ruins - not without producing some ludicrous Disneyland effect.We have lost so much already: Nimrud and Hatra have gone; large parts of Aleppo have been wrecked. What about the Umayyad mosque in Damascus - is that to be condemned for having gorgeous figurative Byzantine mosaics? Must we prepare ourselves for the loss of Leptis Magna?For me, Palmyra embodies the great ideas we owe to the Greeks and the Romans: openness, generosity to other cultures - and above all the ideal of religious and intellectual freedom and tolerance. That is worth fighting for.This is not a clash of civilisations. It is a struggle between civilisation and nihilism, and a fight we must win. ..