Evidentemente, el doctor Jekyll y Mr. Hyde son una indagación en la dualidad de la naturaleza humana. Analiza la dualidad expresada no solo en Jekyll/ Hyde, sino también en Utterson, Poole y en la ciudad de Londres.

Jekyll and Hyde are not the only examples of duality in the novel. The city of London is also portrayed in contrasting terms, as both a foggy, dreary, nightmarish place, and a well kept, bustling center of commerce. Indeed, just as men have both positive and negative qualities, so does society.