My eyes come to rest on a young couple. One towel for the two of them.

I want to be like them!

The couple look like dozens of others. So happiness isn’t that hard to achieve. You just have to be twenty years old, which happens to everyone. You just have to look beautiful with your clothes off, which almost everyone is when they’re twenty, particularly when they have a sun tan. A boy and a girl, gazing into each other’s eyes and holding hands, and caressing each other, and admiring each other’s bums when they get up to go for a swim, and smiling at each other, and even laughing, paying attention to each other. They must be vaguely aware that you shouldn’t spoil those moments because they’re the best in your life and you won’t get them back. So you savour them, you fall in love, you love each other, it’s as simple as that.

My eye wanders back up the beach the way you wander back in time.

I find what I’m looking for. A couple in their thirties.

He’s not bad looking, athletic, on all fours, almost buried in the huge sand-pit that he’s digging with his creamed and hatted children, aged about two and four. He looks as if he’s loving it, even more than the children. She is reading distractedly, and every now and again she looks up and observes them. Happily. She adjusts the hat of the fair-haired little boy, holds out a cool bottle with a nipple on it, swats away a fly.

She’s on guard.

Each of her gestures is sexy. You sense that she’s where she’s always wanted to be. She’s achieved what she wanted to achieve. The apogee. The peak.

She’s keeping watch.

Because all that she owns – her devoted husband, her well-behaved children, her fine body – she wants to keep.

As if it could all last forever.

You’re dreaming, my dear!

My eyes slip away again, I’m spoilt for choice, and I settle a few metres further along.

They are forty. Maybe fifty.

She’s reading, really reading. Concentrating. The last few pages of a giant doorstop. Beside her, he’s getting bored. He’s not bad – tall, greying, something powerful in his expression. But he’s looking elsewhere. On a beach there’s no shortage of pretty things to look at.

Or I take another couple. The same age, but the other way around. He’s lying on his side, back to the sun, in the shade of a parasol, his slightly paunchy belly sliding under him like a deflated balloon. Beside him, still gorgeous, she’s getting bored. Slender, elegant; wearing make-up, nicely turned out. She looks elsewhere. Her eyes come to rest on some children playing in the distance. Hers must be too old; or not old enough to have given her grandchildren. She’s bored, resigned to waiting like this for the rest of her life.

It’s a long downhill slope, my darling …