Part of how Poe managed to amass such an audience with his work is by exploiting themes of paranoia and sensory deception. What better way is there  to grip a reader, keep them invested, than to make them doubt the sanity of the narrator and the stability of the narrative? One of his most aggressive examples is, of course, “The Tell-Tale Heart”- which opens with the narrator desperately trying to convince the reader that he is not, in fact, mad, and that the disease has “sharpened [his] senses,” not dulled them- but the theme manifests in almost every one of his texts. Not just depressions which mirrored his own documented condition, but psychoses, hallucinations, senses of unreality realized through something supernatural or mundane. 

“Ligeia” follows a narrator who struggles with the madness of unexplained death and psychological torment through loss of loved ones. “William Wilson” depends on the paranoia produced by its narrative, as it is only due to the narrator’s increasing lack of connection to the world that he resorts to slaughtering his doppelganger, condemning himself due to his inability to approach his situation rationally. “The Masque of the Red Death” is perhaps less obvious, but if it were not for the partygoers’ drunkenness and mad revelry, events would not have unfolded as they did. Their fervor grants the Red Death entrance to the event as, once again, a severing from reality drives the plot forward. The titular fall in “The Fall of the House of Usher” comes about due to the characters’ utter dependency on the house itself. Their hysteria and in-fighting cause their relationships and home to crumble around them. And, of course, “The Man in the Crowd” is driven by the narrator’s desperation to figure out the one man he can’t manage to read, something which verges into an obsessive paranoia by the end of it.

Poe used the matter of senses and sanity to maintain suspense. Are his narrators unreliable due to their mental health? Are the torments they experience real in the world of fiction, or is everything explainable as a result of their deterioration? I’m curious as to how cognizant Poe was of his own health and how that fed into his use of mental instability as a horror device. Perhaps he recognized it enough to fear it. Or perhaps it was genuinely just that his writing was filtered through his understanding of the world, which would naturally be steeped in his own psychological state.