One of the peculiarities of Western pre-scientific thought is its fondness for certain numbers. For example, consider the tenacity of the four elements that became the four humours or the trinity that also pops up in the works of Freud and Clausewitz. However, the undisputed king of pre-scientific theoretical numbers is the number two. From politics to ethics, metaphysics to epistemology, and cosmology to the philosophy of mind, humanity seems deeply wedded to the idea that reality can be seen as made up of two different kinds of things. I suspect that this strange fetish has its roots in some banal fact about us as a species; perhaps just as our fondness for base-10 arithmetic stems from having ten fingers, perhaps our love of dualisms comes from the fact that we can all hold up our hands and say “on the one hand… but on the other…”. Indeed, the near-universality of the concept of the ‘duality of man’ is unarguably behind the enduring popularity and the flexibility of Robert Louis Stevenson’s novella Strange Case of Dr Jekyll and Mr Hyde (1886).
Over the years, the story of a Victorian scientist who unlocks his darker side has been interpreted in a number of different ways. As well as the original duality of man as a mixture of good and evil, Jekyll and Hyde have also been used as personifications of introverted intelligence vs. extroverted cunning, superego vs. id and as metaphorical explorations of the use of drugs. However, while it would be interesting to compare and contrast all of the different tellings of Stevenson’s story, this review will deal only with one; the 1931 adaptation directed by Rouben Mamoulian and starring Fredric March, an adaptation that deals with the tension between man as an animal and man as a civilised being.