In one descriptive and horrible detail, the narrator addresses the judges who condemn him to death. He specifically describes his impression of their lips, which become seemingly inhuman and oddly nightmarish in his near-delirium. He says,

I saw the lips of the black-robed judges. They appeared to me white—whiter than the sheet upon which I trace these words—and thin even to grotesqueness; thin with the intensity of their expression of firmness—and immovable resolution—of stern contempt of human torture [....]. I saw them writhe with a deadly locution. I saw them fashion the syllables of my name; and I shuddered because no sound succeeded.

Lips aren't white, as they usually have at least a little pigment as well as plumpness. However, to the narrator, his judges' lips are so white and thin, and when he describes them as "writh[ing]" they almost call to mind snakes: a particularly upsetting image.

A second horrible image comes quickly on the former's heels. The narrator says,

And then my vision fell upon the seven tall candles upon the table. At first they wore the aspect of charity, and seemed white slender angels who would save me; but then, all at once, there came a most deadly nausea over my spirit, and I felt every fibre in my frame thrill as if I had touched the wire of a galvanic battery, while the angel forms became meaningless spectres, with heads of flame [...].

First, he uses a metaphor, comparing the candles to angels who might be comforting in this, his hour of need; however, his next simile destroys this possibility. He feels as though he's touched a battery and been electrified by it, so agitated does he feel. Finally, he returns to the metaphor, and now the candles are not angels but horrifying spirits with heads made of fire.

But before the narrator can even adjust to these perceptions, he says,

[...] the judges vanished, as if magically, from before me; the tall candles sank into nothingness; their flames went out utterly; the blackness of darkness supervened; all sensations appeared swallowed up in a mad rushing descent as of the soul into Hades. Then silence, and stillness, and night were the universe.

This third horrible detail describes a darkness so black, which comes upon him so unexpectedly and suddenly, that he can sense absolutely nothing around him. Now totally deprived of two of his senses, the narrator is essentially sightless and deaf: to plunge so deeply into this darkness and silence would be quite horrifying.

He swoons and awakens, but keeps his eyes shut. When he finally develops the strength to open them, he says,

My worst thoughts, then, were confirmed. The blackness of eternal night encompassed me. I struggled for breath. The intensity of the darkness seemed to oppress and stifle me. The atmosphere was intolerably close.

In this fourth horrible detail, the narrator describes the awful oppressiveness of the darkness. It is as though, with the loss of his sight in this terrifying "eternal night," his sense of touch becomes overwhelmed. He can physically feel the darkness, and it seems to press down on him.

He swoons again, and

Upon recovering, I at once started to my feet, trembling convulsively in every fibre. I thrust my arms wildly above and around me in all directions. I felt nothing; yet dreaded to move a step, lest I should be impeded by the walls of a tomb.

This fear, the terror of being buried alive, is a fairly common one, something many of us might relate to or, at least, understand. To be so blind and to have such a fear, not being able to see one's hand in front of one's face, let alone where and if there are walls and how close they are, is horrible.

The narrator later describes the work of another sense:

[...] my forehead seemed bathed in a clammy vapor, and the peculiar smell of decayed fungus arose to my nostrils.

Rendered blind by the dark and deaf by the utter silence, this horrible detail describes what he can smell—a terrible, stomach-churning smell of rotting organic matter.

There are so many to choose from in this gothic short story. It might be worth thinking about some of the following points that add a great deal to the amount of horror and fear in this tale:

1) The pit that the narrator only finds by chance when he trips over just before he walks into it when his prison is plunged into darkness.

2)The way his food and drink is obviously drugged so that he can be controlled and moved so further torture can be set up for him.

3) The description of him being tied up as he watches the pendulum descend.

4) The description of the rancid fat that he rubs into his cords that bind him.

5) The idea of the rats jumping on top of him as they gnaw his cords.

6) Lastly, the final section of the novel, when the hot walls of the prison press in, pushing him ever closer to falling into the pit.

What is key above all else is to note that these are tortures that are terrible and psychologically oppressive, as the narrator describes when he talks about the Inquisition:

To the victims of its tyranny, there was the choice of death with its direst physical agonies, or death with its most hideous moral horrors. I had been reserved for the latter. By long suffering my nerves had been unstrung, until I trembled at the sound of my own voice, and had become in every respect a fitting subject for the species of torture which awaited me.

It is the "hideous moral horrors" that the speaker suffers that make this tale truly terrible, and his description of himself as a person who has become "unstrung" is truly disturbing.