'Do you think that if we all had a kind of tracker device, a tiny light that you could see from space, then everyone's paths would loop and intertwine as ours have?" It's the question asked by Tess, the heroine of Miss You, a novel out this week which is being hailed by its publisher as the next One Day - the 2009 bestseller in which two friends meet on the same day of each year before finally falling in love.
Following on from a lucrative deal in the UK, there has already been a "pre-emptive" bid in the US, and a subsequent scramble to buy it in 24 other countries.
The author, Kate Eberlen, 58, is as amazed as anyone at the response.
"When I wrote it, I had no idea if it would even sell," she says.
The central idea of Miss You is that two young people - Tess and Gus - meet by chance in Florence when they are 18. They are tourists, and Tess and her friend ask Gus to take a photo of them. The story tracks the two over the next 16 years, during which time their paths "cross" again and again but without them knowing it.
(When Gus is having passionate sex in an aeroplane lavatory, Tess and her little sister, who has Asperger's, are waiting outside.) The natural progression of the novel, of course, is that the two end up together.
"I've always been fascinated by how many lives there are in which paths cross, how many encounters we have or almost have," says Eberlen.
"And then when I was coming up to London one day, I was looking out of the window at all those rows of houses and wondering who lives there, if their lives had ever crossed with mine. I had this thought, 'What if there were two people who were kind of right for each other but their paths kept crossing and missing'."
It's not a new idea of course - the 2001 film Serendipity, starring Kate Beckinsale and John Cusack, is based on exactly this power of "fortunate happenstance" - but it is one that is endlessly enduring. Why do we all love the idea that the universe is acting out some bigger plan to bring together two people "destined" for each other?
Eberlen says: "I'm not sure I'd ascribe it to 'fate'. I think it is more about luck - and it is so much to do with timing, because in the case of my characters, if they'd have got together when they were 18, it wouldn't have worked at all."
The role of chance, luck and timing was never more relevant than in the beginning of Eberlen's own marriage. Having grown up in Hitchin, outside of London, she went on to St Anne's College, Oxford, where she read Classics. In her first year, she attended a party in Hertford College's cricket pavilion. Her husband-to-be, Nick - whom she was only to meet properly in 1991, aged 33 - was also there.
Over the ensuing 14 years, during which he was teaching English abroad, he would occasionally appear at various friends' parties, but nothing happened. In fact, Eberlen developed a dislike-at-a-distance. Finally, aged 33, grief-stricken from the loss of her father and working in publishing, she agreed to host a party in her new flat in London and allowed her friends to pick the guest list. "I [asked] 'Who's coming?' and they gave a long list of names and then said 'and Nick'. And I said, 'Oh no! Not that prat who lives in Egypt!'
"I don't know what it was," Eberlen continues, "but when he arrived we just started talking. He was a much more grown-up person than I remembered and I suppose I was more mellow because I'd had so much sadness in my life. We talked all night," she pauses, "and he never left the flat again. A year to that day we got married." They have now been married for 24 years, and have a 20-year-old son.
Eberlen had a series of novels published when her son was growing up, but then moved into teaching. Miss You was her first foray back into writing after several years off.
Was the book based on her own relationship with her husband? Not consciously, she says, but "it must have been in there somewhere. What was really key for us was this issue of timing. During all those 14 years, I never once thought we'd have been suitable for each other.
"When we finally got together, I remember thinking, 'Goodness, he's really lovely'."