Sometimes when we first meet a person who is to change the course of our lives, we don’t even realize it. And yet, this sort of phenomenon — more or less the opposite of love at first sight — though it is perfectly ordinary, in accord with the bulk of human experience, deeply offends our common sense. When it comes to matters of destiny, we have a strong, irrational, and all-too-telling preference for the clarity of fate. We would like such momentous meetings to be neatly written in the stars: for such things to be as obvious as Orion in the night sky. After all, how could we fail to see the very light that’s to lead us?