For the past year or so I've been learning to do magic. I'm no good at it yet, as unwilling audience members (i.e. friends & polite colleagues) will eagerly testify. But I have learnt one secret.

And by magic, I mean card tricks specifically. I'm really not interested in making coins appear from behind your ear or pouring pounds of salt onto your table. Just a plain deck of cards and some sleight-of-mind.

What I really suck at most is keeping the secret of the trick. That's simply impossible. I'll do a (passable) double-lift or a blind shuffle and then promptly show how its done. Even as I reveal it, part of my mind is saying "DON'T!" But I simply can't help myself.

Not everyone has this problem. Once at a festival I was crowd-watching, a bewildering array of vignettes of human behaviour playing out all around me. I noticed a middle-aged man standing quietly on one side, clearly watching the foot traffic too. A pick pocket, perhaps? Some other, more insidious, kind of predator? Piqued, I began to look where he was looking. Then I noticed he was signalling, fingers splayed out in different configurations as his hand hung casually at his side. Somewhere in the crowd, then, a confederate! Could this be a master thief and his pilfering protégé? It's hard to be covert when you look like I do, but I sidled closer anyway.

To my utter delight, the miscreant turned out to be a magician. He was working with a younger performer (his son, I assume) and was selecting candidates from the oncoming crowd. Eventually I struck up a conversation - finding a magician in the wild was just too tempting to pass up. I dropped names and passed on obscure titbits from the history of magic in an attempt to win his trust. I went on and on.

For example, I said, David Copperfield's (then) recent flying illusion - isn't that awesome! But what do you think about X, Y, and Z - things I considered a dead giveaway that showed how it was done. What, I asked, do you think of them apples!?

Conspiratorially, he leaned closer, eyes darting sideways. His lips parted and my heart pounded.

"Can you keep a secret?" he asked quietly.

Flushed, I leant in, almost cheek to jowl.

"Yes!" I whispered, voice cracking.

He glanced about. Nobody within ear-shot. I could almost feel his body heat, we were that close.

"So can I," he said softly.

If I'd had a guillotine, I would have beheaded the bastard.

But at least I learnt his secret, for which I'm very grateful.

I've also learnt that being a scientist is utterly unlike being a magician. Although both deal with secrets and attempt to master them, the scientist in me has an urgent need to share.

Revealing a secret doesn't unweave the rainbow, it intensifies the colours. It allows each to be savoured and appreciated, and then recombined in new and surprising ways.

This is my secret, for which I'm very grateful.