ONCE more in the last 48 hours we have seen the mindless horror of Islamic State scrawled across the face of the globe.
Like all of its acts of terror it is notable not just for its tragedy but for its idiocy: the randomness of the target, the innocence of the victims and the moronic ideology of the cause.
Perhaps the only sliver of condolence in the carnage is that this, like its other DIY attacks, is a sign that ISIS is getting desperate. Its so-called caliphate in Iraq and Syria is crumbling, it is losing the battle against real soldiers, and so it tries to distract us with the murder of innocent men, women and children. What godless cowards they truly are.
And yet even when these barbarians are expunged from the places they stole, some things will never be the same.
For part of the mission of extremists is not just to destroy the present but to destroy the past as well. It is not just the lives of people they wish to wipe out but the memory of them ever having existed.
It is for this reason that ISIS takes such joy in the deliberate destruction of priceless historical treasures which humanity will never be able to recover, including the complete desecration of whole ancient cities.
For anyone with even a passing concern for the human race this is physically sickening.
It is the same darkly Orwellian ideology that fuelled Nazi book-burning campaigns that targeted Jewish, liberal and socialist works and medieval popes destroying whole libraries of priceless ancient texts because they were deemed pagan. For the zealot it is not enough to control and kill the present - one must also control and kill the past.
It is for this reason that the destruction of any historical monuments or artefacts should make humanity's collective blood run cold.
And this has been brought into sharp relief again this week with the tragic and disgraceful events in Charlottesville, Virginia, where - just like those who died in Barcelona - an innocent woman lost her life at the hands of a hate criminal.
There is no excuse for what happened to Heather Heyer. I hope her killer rots in jail.
But the question of how countries like America and Australia deal with the dark shadows of their past - indeed how the whole human race deals with its history - still remains.
The ostensible conflict that led to Heyer's death began over the presence of a statue of Confederate General Robert E. Lee in a public park. But of course the statue is really just a lightning rod for the unrest and division that has permeated Donald Trump's short reign as president.
The real problem is not Lee - who died almost a century and a half ago - but Trump, who remains very much alive and kicking.
Certainly Lee was not a good man - he not only fought for the rights of slave-owners but was a slave owner himself and by some reports a very cruel one. However he is also a source of fascination for scholars and a critical figure in United States history. Should all memorials to him be vapourised from public space?
Indeed, if the owning of slaves is the threshold for historical annihilation then protesters would also have to tear down every statue of George Washington and Thomas Jefferson. Even the great Benjamin Franklin owned slaves before converting to the abolitionist cause
Nor would it stop there. Every Ancient Roman of any standing owned slaves, and so we would have to destroy every statue of Julius Caesar, Augustus Caesar, the philosopher-emperor Marcus Aurelius - the whole lot. Just as ISIS is doing, for that matter.
Or if it was other bad behaviour that required expunging from the record France would have to blow up not just every bust of the dictator Napoleon but also the Arc de Triomphe. In fact if they wanted to extinguish his memory they'd have to level Paris altogether.
Or maybe Napoleon was a revolutionary hero. Ask Oliver Cromwell - he is regarded by some as a revolutionary hero and others as a committer of genocide. His statue stands proudly outside the UK Houses of Parliament.
And in Sydney we would have to bulldoze the Archibald Fountain and abolish the Archibald Prize, whose namesake presided over The Bulletin magazine and the deeply racist content therein.
The fact is that if only the morally pure were remembered in history we would have no history at all. Perhaps activists should focus their efforts on improving the future instead of rewriting the past.
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