When reason returned with the morning – when I had slept off the fumes of the night's debauch – I experienced a sentiment half of horror, half of remorse, for the crime of which I had been guilty (8).
Unfortunately, this period of "reason" does not last. By the time night rolls around all that guilt and horror seems like a dream, and the cycle begins anew. This shows how our judgment isn't something stable or fixed. It moves and changes depending on the circumstances.
It was this unfathomable longing of the soul to vex itself – to offer violence to its own nature – to do wrong for the wrong's sake only […] (9).
Is the narrator bringing this up as part of his possible insanity defense, or is he onto something? Do people do things simply because they know they are wrong? Do people hurt themselves and others on purpose, for the sake of hurting them? How do we judge such people?
[…] it was now, I say, the image of a hideous -- of a ghastly thing -- of the GALLOWS! -- oh, mournful and terrible engine of horror and of crime -- of agony and death! (20)
The narrator is, of course, referring to the shape of the white spot on the second cat's fur. As we learn in the last paragraph of the story, the gallows is also where he's headed, unless he gets a last minute pardon, or can prove he's insane. How you feel about the narrator's plight depends on how you feel about the death penalty.
But this blow was arrested by the hand of my wife. (23)
There is a sad and brutal justice at work here. The woman dies protecting an animal who can't protect itself. Surely her situation didn't escape notice from the neighbors. The man is even afraid to move her body because of them. Unfortunately, there was no law against what the man was doing.
Upon its head, with red extended mouth and solitary eye of fire, sat the hideous beast whose craft had seduced me into murder, and whose informing voice had consigned me to the hangman. (32)
At the very end here, the man puts all the blame on the cat, and, in a roundabout way is arguing that the cat, not the man, belongs in the jail cell waiting for the gallows. Still, there is a sense of justice in this moment, if only because the cat is still alive.