There are eight billion people in the world. Is it possible that one — and only one — is perfect for each of us?

It’s among the most fanciful of notions, as well as one of the most enduring; this is almost certainly because it flies in the face of statistical likelihood, not despite it. And while there’s no reason soulmates can’t be platonic, the concept is most often thought of in the romantic sense — and it is indeed a romantic idea.