Quite a lot of what passes itself off as a dialogue about our society consists of people trying to justify their own choices as the only right or natural ones by denouncing others’ as selfish or pathological or wrong. So it’s easy to overlook that hidden beneath all this smug certainty is a poignant insecurity, and the naked 3 A.M. terror of regret.

The problem is, we only get one chance at this, with no do-overs. Life is, in effect, a non-repeatable experiment with no control.

Watching our peers’ lives is the closest we can come to a glimpse of the parallel universes in which we didn’t ruin that relationship years ago, or got that job we applied for, or got on that plane after all. It’s tempting to read other people’s lives as cautionary fables or repudiations of our own.