Stevenson's story also endures as a landmark in the evolution of psychological fiction, anticipating the psychic conflicts of doubles or alternating personalities in such notable works as Dostoevsky's The Devils (1872), Conrad's "The Secret Sharer" (1912), and Nabokov's Pale Fire (1962). Written autotherapeutically in the aftermath of a nightmare, Dr. Jekyll and Mr. Hyde immediately popularized the concept of alternating personality years before Freud began publishing his first papers on psychoanalysis.

For police, press and public, Stevenson's tale provided a convenient label-name for any homicidal wolf in sheep's clothing.                      (from his Introduction, page 3)