First the Pope resigns, breaching centuries of tradition.

And then Oscar Pistorius, the Blade Runner, idol to millions, is arrested and charged with the premeditated murder of his girlfriend, Reeva Steenkamp.

Both events caused a sharp intake of breath; each seemed as unlikely as the other.

The South African double amputee is the most famous disabled athlete in the world; thousands of children facing a future of disability would have felt a little less limited and a little more inspired, thanks to his amazing example on the track.

It just seemed impossible he could have picked up a gun and shot someone.

The scenes in the courthouse in Pretoria, with Pistorius sobbing uncontrollably as his defence lawyer explained he had no intention of killing Steenkamp, and that it was all a terrible accident, are inconceivable and shocking to anyone who had seen him competing.

It was also difficult to believe the stories that emerged the second the news broke, stories that depicted Pistorius as an adrenalin junkie who loved guns; a man with a hot temper and a pugnacious nature lurking beneath his diplomatic surface.

In the terrible story of Pistorius, there is not only the shock of the act itself, but also of the revelation someone people thought they knew was not quite as he seemed.

In this way, and this way alone, it echoes other tragic tales of sportsmen once placed on a pedestal who have shown their feet of clay.

People thought Tiger Woods was a god until he crashed his car into a tree one night after an argument with his then wife, Elin Nordegren, and the facade of perfect family man cracked to reveal a serial adulterer.

Ryan Giggs looked like the perfect role model and spent a great deal of money protecting that image through the courts to stop the emergence of his affairs, including one with his sister-in-law.

The most terrifying allegations about Lance Armstrong are not simply his use of performance-enhancing drugs to make him the best, but the bullying and intimidation he used to preserve his superclean, supercool image.

Those stories are hard to square with his previous public image as a cancer survivor intent on doing good; no wonder his foundation no longer bears his name.

I am not suggesting having an affair is the same as cheating at sport or that either is equivalent to a murder charge but in their different ways each revelation shows how little we know about these men — and it usually is men — whom we endow not only with superhuman sporting ability but extraordinary personal qualities.

Yet these figures in the public eye are ultimately unknowable.

They show us only what they want us to see.

Despite numerous post-match interviews, their intimate thoughts, their vulnerabilities, their ugliness are all perforce hidden from view.

If they were not, their sporting ability would be overshadowed by the unsavoury aspects of their characters and their lives.

What fools we are to put such faith in them.

The nature of sporting success requires a high degree of narcissism and arrogance, an inflated sense of your own worth, and a single-minded pursuit of your goals.

Indeed, it requires many of the qualities that actually work against goodness, kindness and being nice and loyal to the people closest to you.

This does not make all sportsmen bad.

Still less does it make them likely to shoot someone.

But it is a salutary reminder that we should not necessarily admire them for anything more than what we know they can do in sporting terms.

We should praise their single-mindedness, natural ability, honed talent.

But it is stupid and unreasonable to expect they should somehow reward us for our devotion by leading blameless lives.