One of the great mysteries of the universe is the birthday phenomenon. You know, the one that says that if you're in a group of twenty-three people, there's a 50% chance that two of you will have the same birthday. OK, that's interesting.

But what's more interesting is how likely you are to discover that two of you have the same birthday.

Think about it.  Coincidences exist all the time. You could be sitting between two people on the tube who both have the same birthday as you, but you're unlikely ever to discover it.  The person you've been talking to at a party might have four children with the same names as yours. But the trick is to get there.

So there are two tiers of coincidence. The ones that merely exist (covert coincidence) and the ones you manage to uncover (overt coincidence).

I know a woman whose twins are named Chester and Lois. Like my parents.

Fairly odd.

But really odd, was the guy I met at a party at Le Train Bleu in New York City thirty years ago, with whom I talked for about ten minutes, discovering not only that we were from the same tiny town two hundred miles away and that we'd gone to the same school, but that we were both in the same playground when we heard that JFK had been shot -- by means of a child running through the playground shouting "Kennedy's dead he got shot in the head!" It was 1963.  I was seven. How on earth did we get there?  And so fast?

But really odd, was the guy I met at a party at Le Train Bleu in New York City thirty years ago, with whom I talked for about ten minutes, discovering not only that we were from the same tiny town two hundred miles away and that we'd gone to the same school, but that we were both in the same playground when we heard that JFK had been shot -- by means of a child running through the playground shouting "Kennedy's dead he got shot in the head!" It was 1963.  I was seven. How on earth did we get there?  And so fast?

But really odd, was the guy I met at a party at Le Train Bleu in New York City thirty years ago, with whom I talked for about ten minutes, discovering not only that we were from the same tiny town two hundred miles away and that we'd gone to the same school, but that we were both in the same playground when we heard that JFK had been shot -- by means of a child running through the playground shouting "Kennedy's dead he got shot in the head!" It was 1963.  I was seven. How on earth did we get there?  And so fast?

But really odd, was the guy I met at a party at Le Train Bleu in New York City thirty years ago, with whom I talked for about ten minutes, discovering not only that we were from the same tiny town two hundred miles away and that we'd gone to the same school, but that we were both in the same playground when we heard that JFK had been shot -- by means of a child running through the playground shouting "Kennedy's dead he got shot in the head!" It was 1963.  I was seven. How on earth did we get there?  And so fast?

But really odd, was the guy I met at a party at Le Train Bleu in New York City thirty years ago, with whom I talked for about ten minutes, discovering not only that we were from the same tiny town two hundred miles away and that we'd gone to the same school, but that we were both in the same playground when we heard that JFK had been shot -- by means of a child running through the playground shouting "Kennedy's dead he got shot in the head!" It was 1963.  I was seven. How on earth did we get there?  And so fast?

But really odd, was the guy I met at a party at Le Train Bleu in New York City thirty years ago, with whom I talked for about ten minutes, discovering not only that we were from the same tiny town two hundred miles away and that we'd gone to the same school, but that we were both in the same playground when we heard that JFK had been shot -- by means of a child running through the playground shouting "Kennedy's dead he got shot in the head!" It was 1963.  I was seven. How on earth did we get there?  And so fast?

But really odd, was the guy I met at a party at Le Train Bleu in New York City thirty years ago, with whom I talked for about ten minutes, discovering not only that we were from the same tiny town two hundred miles away and that we'd gone to the same school, but that we were both in the same playground when we heard that JFK had been shot -- by means of a child running through the playground shouting "Kennedy's dead he got shot in the head!" It was 1963.  I was seven. How on earth did we get there?  And so fast?

But really odd, was the guy I met at a party at Le Train Bleu in New York City thirty years ago, with whom I talked for about ten minutes, discovering not only that we were from the same tiny town two hundred miles away and that we'd gone to the same school, but that we were both in the same playground when we heard that JFK had been shot -- by means of a child running through the playground shouting "Kennedy's dead he got shot in the head!" It was 1963.  I was seven. How on earth did we get there?  And so fast?

But really odd, was the guy I met at a party at Le Train Bleu in New York City thirty years ago, with whom I talked for about ten minutes, discovering not only that we were from the same tiny town two hundred miles away and that we'd gone to the same school, but that we were both in the same playground when we heard that JFK had been shot -- by means of a child running through the playground shouting "Kennedy's dead he got shot in the head!" It was 1963.  I was seven. How on earth did we get there?  And so fast?

But really odd, was the guy I met at a party at Le Train Bleu in New York City thirty years ago, with whom I talked for about ten minutes, discovering not only that we were from the same tiny town two hundred miles away and that we'd gone to the same school, but that we were both in the same playground when we heard that JFK had been shot -- by means of a child running through the playground shouting "Kennedy's dead he got shot in the head!" It was 1963.  I was seven. How on earth did we get there?  And so fast?

But really odd, was the guy I met at a party at Le Train Bleu in New York City thirty years ago, with whom I talked for about ten minutes, discovering not only that we were from the same tiny town two hundred miles away and that we'd gone to the same school, but that we were both in the same playground when we heard that JFK had been shot -- by means of a child running through the playground shouting "Kennedy's dead he got shot in the head!" It was 1963.  I was seven. How on earth did we get there?  And so fast?

But really odd, was the guy I met at a party at Le Train Bleu in New York City thirty years ago, with whom I talked for about ten minutes, discovering not only that we were from the same tiny town two hundred miles away and that we'd gone to the same school, but that we were both in the same playground when we heard that JFK had been shot -- by means of a child running through the playground shouting "Kennedy's dead he got shot in the head!" It was 1963.  I was seven. How on earth did we get there?  And so fast?

But really odd, was the guy I met at a party at Le Train Bleu in New York City thirty years ago, with whom I talked for about ten minutes, discovering not only that we were from the same tiny town two hundred miles away and that we'd gone to the same school, but that we were both in the same playground when we heard that JFK had been shot -- by means of a child running through the playground shouting "Kennedy's dead he got shot in the head!" It was 1963.  I was seven. How on earth did we get there?  And so fast?

But really odd, was the guy I met at a party at Le Train Bleu in New York City thirty years ago, with whom I talked for about ten minutes, discovering not only that we were from the same tiny town two hundred miles away and that we'd gone to the same school, but that we were both in the same playground when we heard that JFK had been shot -- by means of a child running through the playground shouting "Kennedy's dead he got shot in the head!" It was 1963.  I was seven. How on earth did we get there?  And so fast?

But really odd, was the guy I met at a party at Le Train Bleu in New York City thirty years ago, with whom I talked for about ten minutes, discovering not only that we were from the same tiny town two hundred miles away and that we'd gone to the same school, but that we were both in the same playground when we heard that JFK had been shot -- by means of a child running through the playground shouting "Kennedy's dead he got shot in the head!" It was 1963.  I was seven. How on earth did we get there?  And so fast?

But really odd, was the guy I met at a party at Le Train Bleu in New York City thirty years ago, with whom I talked for about ten minutes, discovering not only that we were from the same tiny town two hundred miles away and that we'd gone to the same school, but that we were both in the same playground when we heard that JFK had been shot -- by means of a child running through the playground shouting "Kennedy's dead he got shot in the head!" It was 1963.  I was seven. How on earth did we get there?  And so fast?

I heard Hilary Mantel speak at the Oxford Literary Festival last year, and she described ideas circling the airspace above her head like planes waiting to be called in to land.

I'll write a book about overt and covert coincidence someday soon. It's been circling long enough.