Discuss the theme of reason vs. madness in "The Pit and the Pendulum."

The dichotomy between reason and madness can be said to exist on at least two levels in Poe's story. The narrator himself is given to a rational dissection of his own thoughts and of his experience in the torture chamber. He gives a detailed analysis of what it is like to emerge from unconsciousness, and analogizes this condition with death:

In the return to life from the swoon there are two stages: first, that of the sense of mental or spiritual; secondly, that of the sense of physical, existence. It seems probable that if, upon reaching the second stage, we could recall the impressions of the first, we should find these impressions eloquent in memories of the gulf beyond. And that gulf is—what? How at least shall we distinguish its shadows from those of the tomb?

As he lies in the chamber the narrator continues his speculations on his situation, imagining himself to be in a middle state between life and death:

The sentence had passed; and it appeared to me that a very long interval of time had since elapsed. Yet not for a moment did I suppose myself actually dead. Such a supposition, notwithstanding what we read in fiction, is altogether inconsistent with real existence;—but where and in what state was I?

In his narrative, one senses an attempt to use reason to analyze what is being inflicted upon him. But there is also a kind of madness about the descriptions he gives us. The voice is (unsurprisingly) similar to that in other Poe stories such as "The Black Cat" and "The Tell-Tale Heart," in which the narrator is obviously psychotic. In most of Poe's tales, we see a typical feature of Dark Romantic fiction, where the difference between illusion and reality is blurred, or the author's point may be that ultimately, there is no difference between the two. Yet from a historical standpoint, there is no cause to doubt that victims of the Inquisition were subjected to the levels of torture described by Poe. The story is a meditation upon the mad brutality that men are capable of inflicting upon each other.
This leads us to the second level of the reason vs. madness theme. The perpetrators of the Inquisition were themselves insane, by any reasonable standard. The whole concept of torturing and murdering people as a means of defending religion is, at the very least, a kind of hypocrisy based on madness. The narrator, as a victim, and regardless of the madness into which he may have been plunged himself, represents rationality in opposition to the insanity of those who are torturing him. It is a demonic, almost supernatural madness that the narrator sees in the judges who have condemned him:

I saw the lips of the blackrobed 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—of immovable resolution—of stern contempt of human torture.

The resolution of the story in the final pages has sometimes been criticized as too sudden and improbable to make any real sense:

There was a discordant hum of human voices! There was a loud blast as of many trumpets! There was a harsh grating as of a thousand thunders! The fiery walls rushed back! An outstretched arm caught my own as I fell, fainting, into the abyss. It was that of General Lasalle. The French army had entered Toledo. The Inquisition was in the hands of its enemies.

One wonders if Poe's powers of invention failed him at this moment. The ending is similar to the cliche of "the cavalry coming over the hill" to save the heroes in movies that take place in the old West. But in "The Pit and the Pendulum," could the close of the story be an expression of the ultimate madness, that out of nowhere this seemingly impossible rescue occurs?