Who can resist a diary? They promise intimate revelations—the confidences that let us glimpse the human condition, which we turn to literature for but don’t always find—alongside the rhythms and texture of life as we live it, day by day. And each diary is unique; each represents a specific set of circumstances met by a specific mind. It’s fun to dip into John Cheever’s and then Franz Kafka’s, like moving between an icy pool and a hot tub—a pleasant shock.

 At its worst, of course, a diary can be a dutiful recording that fails to come alive. What memoirists and fiction writers do is considerable