What matters most: the loss of 200,000 lives or the threatened destruction of some ancient ruins?
The answer should be obvious, I know - and yet ...
Perhaps it's because I have visited the ancient Syrian city of Palmyra, and have marvelled at the breath-taking beauty of its historic ruins, shimmering as the sun set over the desert.
Perhaps it's because I know they are irreplaceable, that once they have been destroyed, they will never be seen again - even as of course I acknowledge that the same is true of every single Syrian life lost in the past four years of bloodshed.
The threatened loss of a world heritage site brings its own unique brand of sadness. If we have visited the site, or even if we have seen only the pictures, we can identify with it in a way we cannot with those hundreds of thousands of individuals who have died in conflict.
So we mourn what we can identify with, more than with what we can't. Part of me knows that the ruins are merely stone, and that they have already been partially destroyed or mutilated many times in their 2,000-year history. And yet if they are bulldozed to the ground in the coming days, I shall shed a tear for their loss.
Much of what those who care about ancient sites most value is precisely what the IS, or Islamic State, fanatics most despise. We value what links us to the past, what demonstrates to us that long before our own culture was born, there were already architects, artists and poets, stonemasons and carpenters, who created sublime works of lasting beauty. And yes, that there were also religions and deities before those to which we ourselves may subscribe.
That thought is anathema to IS, who seek to obliterate any suggestion that there could have been anything of value in the world before the birth of their own culture and their own religion.
But there's more to their orgy of destruction than that: I suspect that another reason why they enjoy destroying what they know we value is that they know it hurts us so deeply and that we are powerless to stop them.
It is as if a group of fanatics were to seize Rome and threaten to flatten the Colosseum, or take control of Cairo and blow up the pyramids at Giza. Imagine how we would grieve if someone destroyed the great buildings and bridges along the Grand Canal in Venice.
Each archeological treasure is testament to thousands of years of human endeavour to transcend the merely mundane. Whether it's the ancient ruins at Angkor Wat in Cambodia, the Temple of Karnak in Luxor, or the massive Mayan structures at Teotihuacán in Mexico, they remind us that the search for beauty and meaning, for an understanding of our place in the firmament, is not just of our time but of all time.
They are also, of course, as is Palmyra, testament to wealth and power. All new conquerors seek to destroy what they find and to replace it with their own monuments to their own immortality. This, they say, is who we are, and how we can obliterate those whom we defeated. Where now are the Hanging Gardens of Babylon, or the Great Library of Alexandria?
In that respect, IS are just the latest conquerors in a much-conquered land. And if their past behaviour is anything to go by, they will behave in exactly the same way.
So what, I hear you cry, can we do about it? My answer, I fear, is that we can do very little. We can no more protect the ancient ruins of Palmyra than we can the hundreds of thousands of terrified, traumatised human beings whose lives have been destroyed in this brutal war.
And if you think foreign military intervention in Syria on the side of the rebels might have prevented the advance of IS, I would simply urge you to look at what's happening next door in Iraq. There, 12 long years after the US-led invasion, IS fighters have now seized the key city of Ramadi, buoyed at least in part by Sunni ex-Saddam loyalists threatened by the Iranian-backed Shia administration in Baghdad.
Perhaps, though, we can at least reflect on the tragic irony that while we mourn the likely loss of a unique historic treasure in Palmyra, the governments of the EU, including our own, are refusing even to discuss a way to offer shelter to those Syrians and others who have managed to escape the hell which is now their homeland.
Instead, there is talk of destroying the boats into which they have crammed, hoping to reach safe haven in Europe, and of "sending them back to where they came from".
Last year, according to the UN refugee agency, nearly a third of the migrants who risked their lives crossing the Mediterranean came originally from Syria.
Send them back? To Palmyra?