Strange Case of Dr. Jekyll and Mr. Hyde
London Fog vs. Light
Symbolism, Imagery, Allegory
The London fog serves to shroud or veil the city and make it eerie. Fog = obscurity, and the literal fog emphasizes the metaphorical fog surrounding the true identity of Hyde. You’ve also got firelight, lighted lamps, and light in general as the counterpoint to fog because of their safe, illuminating qualities.