The oldest magic trick in the world is probably the cups and balls — three cups on a table, a small ball, and the ball keeps moving between them.

A painting on the wall of a tomb at Beni Hasan in Egypt, made around 2000 BC, appears to show two men doing the trick.

The Roman writer Seneca described it in the first century AD.

Every century since, from Roman street performers to Victorian parlour magicians to modern stars like Penn and Teller, has had its version.

There is no supernatural secret; the trick relies on a fourth ball, hidden from the start, and on the magician being much better at moving their hands than the audience is at watching.

That's it.

Try this: take three cups, one ball, and try to pass the ball from your left palm to your right in a moment when the audience is looking at your left hand.

Do it fifty times and you will start to understand how the last three thousand years of stage magic actually work.