My guess is that this is a trite or tired observation, but it struck me hard as it hasn’t before that the story of Dr. Jekyll and Mr. Hyde could really have been Robert Louis Stevenson’s way of exploring the issue of drug addiction in the 19th century.
The good doctor drinks a concoction of his own making and becomes a different person with base instincts. He finds that he soon has to go to the apothecary for more and more of the ingredients. He must have the potion or he will go out of his mind.
At first, he denies that his drugged self is doing anything terrible. But slowly the evidence grows. Soon he is face to face with the horrible things he has done. Yet still he cannot stop. He must have the potion, he must become Hyde. He must pretend he is only Jekyll. In the end, he is driven into madness by his obsession and his inability to return to his former self.
I saw a fascinating account hypothesizing that it was about Stevenson’s home city of Edinburgh — the good and bad parts of the city during his time there and how some upperclass people were serial murderers or grave robbers by night. Setting the book aside, it was a great history of the city too.