THE awful incident in Derby when a mob encouraged 17-year-old Shaun Dykes to jump to his death from the roof of a shopping centre is one of the nastiest news stories I’ve read in my life.

A group of onlookers gathered to watch while trained negotiators spent three hours trying to coax him down. Some of the mob taunted Shaun, who lived in the Derbyshire village of Kilburn, and shouted: “Go on then, jump!”

Students from Shaun’s college were nearby and heard the goading. According to his head teacher Rob Howard: “One student told me he could not believe people place such little value on life. It’s almost as if they are in a television show. It’s unreal.” He added: “The sad thing is that a couple of the students, if they could have got close enough, felt that they could have made a difference. It’s very traumatic.”

The hateful mob was not made up only of young louts. Astonishingly, middle-aged and middle-class people, ordinary shoppers, rushed to where Shaun had fallen to photograph his body on their mobile phones.

How do we account for such disgraceful behaviour?

I’m afraid the causes are simply the old culprits: human wickedness and human folly. Thinking about this shocking event a few days afterwards, I was struck by the sense that our society has lost the knack of distinguishing between appearance and reality.

We are so much enthralled by the voyeuristic culture of Big Brother and YouTube that we tend to mistake real life events for play-acting. The result is the massive desensitising we saw in the Derby mob.

It struck me also that modern society uncannily resembles the sorts of things that were going on near the fall of the Roman Empire – things which St Augustine condemned in his great book, City of God. The cruelty of the arena, the gladiatorial contests and the deadly games in the Colosseum where spectators would vote by a show of hands on whether a man should have his left foot or his right hand cut off first.

Augustine describes a state in which people are “...unconcerned about the utter corruption of their country – ‘So long as it lasts’ they say – so long as it enjoys material prosperity.”

He goes on: “Full publicity is given where shame would be appropriate; close secrecy is imposed where praise would be in order; decency is veiled from sight; indecency is exposed to view. Scenes of evil attract packed audiences.”

The downfall of the Roman Empire was preceded with a whole series of financial crises. It was overwhelmed by mass immigration and threatened by barbarian violence.

The comparisons with our own time are very striking. Augustine prophesied against “...rulers who are interested not in the morality, but the docility of their subjects; they are regarded not as directors of conduct but as controllers of material things and providers of material satisfaction.”

Doesn’t that make you think of extravagant loans to people who could never afford them; of laws to encourage 24/7 shopping and 24/7 drinking; of the whole world turned into advertisements? A civilisation cannot survive on such debased conduct, on pretend values which are really valueless. If you’re curious as to what will happen to our society next – read St Augustine.

■ Peter Mullen is Rector of St Michael’s, Cornhill, in the City of London, and Chaplain to the Stock Exchange.