From an anonymous London Times 1886 review of Jekyll & Hyde: “Nothing Mr. Stevenson has written as yet has so strongly impressed us…Naturally, we compare it with the sombre masterpieces of Poe, and we may say at once that Mr. Stevenson has gone far deeper. Poe embroidered richly in the gloomy grandeur of his imagination upon themes that were but too material, and not very novel…while Mr. Stevenson evolves the ideas of his story from the world that is unseen, enveloping everything in weird mystery, till at last it pleases him to give us the password.”

“Nineteenth century scientists made extensive studies of mental disorder, especially what was called hysteria — a catch-all term for anxiety disorders, psychosomatic illnesses, and dissociative conditions such as amnesia and multiple personality disorder. These conditions were often seen as manifestations of unconscious states, and in the later decades of the century several theorists developed sophisticated dynamic accounts of mental disorder in terms of unconscious motivations.” (Frankish & Evans 2009)

Frankish, Keith, and Jonathan St. B. T. Evans. “The Duality of Mind: An Historical Perspective.” In Two Minds: Dual Processes and Beyond, 2009, pp. 1–30., doi:10.1093/acprof:oso/9780199230167.003.0001.