The narrator of The Black Cat is slowly but surely driven to madness by the animal that haunts him. I believe this quote shows the narrator succumbing to his withheld insanity with the help of his alcohol. It is in this slip that he looses his old self and becomes something almost unrecognizable to even himself. It is a great show of how a person can change under the right pressed mixture of circumstances and their very being. Poe shows how an ordinary person (in this case: the narrator) is able to be driven mad if pushed by the right trigger (the black cat).