This short novel, published in 1886 by Robert Louis Stevenson (1850-94), may well be more familiar in its many stage, film and television adaptations than in its original form, while 'Jekyll and Hyde' has become the shorthand for a character who seems to have a 'split personality'. Stevenson claimed that the main features of the story came to him in a dream, and he wrote it very rapidly, though ill and bedridden at the time. Priced at one shilling (the genre of macabre and horror stories was known as the 'shilling shocker'), it was an immediate success. Though not the first of Stevenson's works to explore the notion of the divided self, in a period where increasing concern was felt about the possible negative sides of discoveries in both the physical and biological sciences, the story clearly struck a chord, and it has remained popular ever since.