The Mystery of the Literary Double: Why do novelists write about doubles and doubleness instead of multiples and multiplicity, and which one writes about it?

Theoretically, the simplest case of multiple personality is two personalities, but I have never seen a case in which the person had only two personalities.

The first time you meet a person’s alternate personality, you might think that there are only two—the regular self and the alternate personality—but it always turns out that there are more. And most of the personalities are not duplicates in how they look to themselves or each other. The theme of the double makes no sense.

So why does Dostoevsky have The Double, and Stevenson Jekyll and Hyde? Why does Henry James in “The Private Life” have one of a writer’s selves out socializing, while the writer’s other self is back in his room writing? Why does Joyce Carol Oates write about “JCO and I” (after “Borges and I”)? Why does Margaret Atwood write about the writer’s inherent “doubleness” (the one who does the living and the one who does the writing)?

And if there were only two, which of the two would be the one who is telling the reader about this?