Throughout the story, Poe uses visual imagery of flickering light to create an uncertain and frightening atmosphere. When the narrator first glimpses the old man in the crowd, he describes the changing light as the city street grows darker:
The rays of the gas-lamps, feeble at first in their struggle with the dying day, had now at length gained ascendancy, and threw over everything a fitful and garish lustre […] The wild effects of the light enchained me to an examination of individual faces, and although the rapidity with which the world of light flitted before the window, prevented me from casting more than a glance upon each visage, still it seemed that, in my then-peculiar mental state, I could frequently read, even in that brief interval of a glance, the history of long years.
The gas-lamps create a spooky and frightening mood, and Poe’s characterization of the gas-lamps gaining “ascendancy” over the day suggests a triumph of evil over good, with the flickering light of gas-lamps representing evil and corruption while the clear, natural light of the sun represents goodness and purity. Gas-lamps could also be read as a symbol of all things industrial and urban, since they were invented during the Industrial Revolution to light city streets, while sunlight could be read as a symbol for the natural and preindustrial.
The narrator also describes the flickering lamp-light as bringing out “every species of infamy from its den,” referring to the people he deems dangerous or otherwise unsavory. In turn, the narrative associates gas-lamps with crime and danger.
Significantly, the flickering lamp-light obscures the narrator’s vision throughout the story, preventing him from “casting more than a glance” on anyone’s face. This makes it unclear what is actually happening in the story and what the narrator is imagining. Since the narrator glimpses the old man in the crowd while his vision is obscured, there's a possibility that the narrator is hallucinating or otherwise imagining an old man that isn’t actually there. As soon as the sun sets and the gas-lamps are switched on, all becomes obscured—there’s even a “thick humid fog” that rolls over the city as the night progresses. This obscurity throws the reliability of the narrator’s account into question, since he can’t see clearly enough to be a reliable witness.
At one point, the narrator calls the old man a “fiend,” thus comparing him to the devil. This, combined with the flickering lamplight (which, with its association with evil, could be an analogue for the flames of hell), creates a scary, hellish atmosphere and gives the impression that the old man is the devil himself leading the narrator to the depths of hell.
As the narrator pursues the old man through London, he gradually moves from more affluent areas of the city into a neighborhood stricken by poverty. Poe uses vivid imagery of decay and desolation to evoke the feelings of unease that the narrator experiences as he enters a potentially dangerous neighborhood:
It was the most noisome quarter of London, where every thing wore the worst impress of the most deplorable poverty, and of the most desperate crime. By the dim light of an accidental lamp, tall, antique, worm-eaten, wooden tenements were seen tottering to their fall, in directions so many and capricious that scarce the semblance of a passage was discernible between them. The paving-stones lay at random, displaced from their beds by rankly-growing grass. Horrible filth festered in dammed-up gutters. The whole atmosphere teemed with desolation.
In this passage, Poe is appealing to readers’ sense of sight to evoke a scene of dereliction, decay, and mystery. The “dim light of an accidental lamp” casts the scene into obscurity. In unlit or dimly lit streets, the passage suggests, much can remain hidden, including crimes that, conducted outside the well-lit and well-monitored streets of affluent areas, go unobserved and unsolved.
The “tall, antique, worm-eaten tenements […] tottering to their fall” evoke the ruined mansions and dilapidated castles of Gothic fiction. However, Poe has inverted the tropes of 18th-century Gothic literature in this passage. Rather than situating this kind of unsettling fear of the unknown in a rural setting beyond the reach of modernity and civilization, "The Man of the Crowd" spotlights the fearful aspects at the very heart of modern civilization itself: the industrial city. This reflects the rising anxieties about hidden crime and madness that many people felt as they moved to cities during the Industrial Revolution. Prior to the Industrial Revolution, most people would have lived in small towns where they knew everyone. Civilization was a place of familiarity and safety, while all that lay outside of it was unknown and a potential source of danger and terror. However, after the Industrial Revolution, city-dwellers found themselves constantly encountering the unknown in the strangers they shared a city with—people whom they brushed shoulders with in crowded spaces could be as much of a threat as any monster lurking in a dark forest outside the preindustrial town’s bounds. In “The Man of the Crowd,” Poe illustrates this anxiety by drawing a visual parallel between the city buildings of London and a Gothic castle or a dark forest, which his readers would have immediately recognized as sites of danger.
It is also worth noting that everything is askew in this passage—the narrator describes the buildings as falling “in directions so many and capricious that scarce the semblance of a passage was discernible,” and the paving-stones as laying “at random.” This repeated imagery of crookedness suggests that at this point in the story, order has been disrupted, and things are not as they should be. This could be read as a reflection of the criminal activity in this neighborhood, as well as an indication of the narrator’s own disordered mental state.
