In 1960 the Princeton physicist -- and subsequent Nobel Prize winner -- Eugene Wigner raised a fundamental question: Why did the natural world always -- so far as we know -- obey laws of mathematics?

I recently saw images of the hauntingly empty Iraqi town of Qaraqosh, near Mosul, which was taken by ISIS in 2014. It had a population of 50,000 mostly Assyrian Christians, but is now totally abandoned. The militants have used every means to erase the town of its Christian identity defiling and destroying its beautiful church buildings.

But the world slept like Rip Van Winkle, blinkered by the disbelief that the most cultured and educated elite could stoop to the most barbaric behaviour known to mankind. You could count the Davids who dared to challenge the Goliath of the Third Reich on the fingers of one hand. It was slingshots against Panzers and the Luftwaffe. It was Lutheran pastors Niemöller and Bonhöeffer against Hitler and Göring.

Vatican spokesman Federico Lombardi said in a statement that the Pope and the imam had 'mainly addressed the common challenges faced by the authorities and faithful of the major religions of the world.' The Pope presented the Grand Sheikh with a copy of his encyclical, Laudato Si, on climate change and economic inequality. Pope Francis did not publicly mention jihad, or violence in the name of Islam, or freedom of religion, or human rights for Christians in Egypt.