Jim’s had a quadruple bypass, he’s in his mid 70s and lied about his age to get on the dig. A skilled engineer, he coaxes the ancient, paraffin-fuelled Coca Cola fridge back to life –for a day at least. Deanne may be forty five, may be fifty five – hard to tell. She’s had a bit of work done on her face but it’s subtle. Every morning she hangs a mirror from a branch of a tree to do her make up. Fresh from divorce she’s raw but not bitter, just looking for a man to fill the empty space in her life.

Jim and Deanne are kneeling on the ground, in a dusty rock shelter, chatting. Along with several other waifs and strays – mostly Americans –  they’re excavating a Later Stone Age site in Swaziland, southern Africa.

Not everyone’s a mature survivor. Outside a couple of youngsters are standing in the sun, shipped off by wealthy parents for the summer, maybe for the life-changing experience, maybe just to get them off their hands – who knows.

Both boys are seventeen. One’s a nice, kind youngster of average height, average looks and above average charm. The other’s tall, handsome, fretful, impatient – and totally blind. They didn’t travel together and a few days ago they didn’t know each other.

The blind boy – let’s call him Zed – laughs a lot, but it’s not a happy laugh, it’s an echo of the way his gawky frame looks. The other boy, Bob we’ll call him, wears glasses. He’s nervous, tugs a lot on his floppy hat and smiles a cheerful smile.

Today Bob’s looking unhappy. It’s not like him. But he has a problem. We have a problem.

Zed came alone, so we all have to take turns looking after him. Or rather, some of us do. Believe me, not everyone who’s spent a fortune crossing continents is willing to spend their time leading a blind boy around.

Bob, inevitably, bears the brunt of the burden. But an increasingly frustrated,  irritable and un-asked for pal is spoiling the trip of his young lifetime. And it makes Bob miserable to be selfish. See – I said he was a nice kind boy.

So, Tex and I are pondering what to do with Zed who really, really wants to dig.

OK – so how hard can it be?

We send Bob off to dig with the others and set Zed up with a pit to stand in so the surface he needs to dig is at waist height. We give him a small square of his own and hold his hand to show him how to use the trowel.

Blind people develop their other senses to make up for their missing sight, don’t they? Well, maybe it’s true, but maybe it’s just something we made up so we’d feel less guilty, we who are privileged to have a full, working set of sensory apparatus. Anyway, we lay out various stones, bones and artefacts and watch as he feels each one and we describe it.

A few of us take turns standing with Zed, digging with him, feeling finds with him and trying to help him work out how far he has dug, what he has dug, what he has found.

We try. He tries. And he cries. In fact, he howls. He digs great gouges out of his square in anger and frustration and throws the trowel aside in total exasperation.

In the dust of a cave, where colour changes in the soil are important, where different rocks do not really feel that different and a bone feels just like a twig – Zed simply cannot do it.

Fast forward now to 2012….

It’s been a great summer, here in newly Paralympics-mad Great Britain, for overcoming prejudices. The games won the hearts of millions, showed us real people overcoming massive odds to achieve great things – to be the best. No surprise then, to hear someone on the BBC say:

anyone can achieve anything if they set their minds to it.

Listen to me, world. IT IS NOT TRUE.

It is a laudable idea that we can overcome any difficulty that this unfair, sometimes cruel world throws at us. But wouldn’t it be more realistic – and less disappointing – if we believed that each of us, no matter what our ability, can do something wonderful if we put our minds to it? Something that is within our capabilities, whatever they are? That if we can’t, really can’t do something, no matter how hard we try, we’re not failures if we simply change our aspirations?

We can all achieve. We can all respect other people’s achievements for what they are. Now that really would make the world a better place, don’t you think?