I am not going to repeat what you have already read or heard. I am not going to say that what happened in Paris on Friday night was unprecedented horror, for it was not. I am not going to say that the world stands with France, for it is a hollow phrase. Nor am I going to applaud François Hollande’s pledge of “pitiless” vengeance, for I do not believe it. I am, instead, going to tell you that this is exactly how civilisations fall.

Here is how Edward Gibbon described the Goths’ sack of Rome in August 410AD: “. . . In the hour of savage licence, when every passion was inflamed, and every restraint was removed . . . a cruel slaughter was made