The Tell Tale Heart Response

I think that by far the most interesting thing from Poe's "The Tell Tale Heart" is the narrator/killer's process of self-justification as he rationalizes his deranged thought process that is inspired by his neighbor's ominous' eerie eye.  It shocked me how frequently the narrator would say things like "you think me mad...not so when you hear this or that," and how literally every time "this or that" immediately translated into an almost perfect, Merriam-Webster dictionary caliber definition of insanity.  For example, the narrator prefaces his description of how he mutilates the body after killing the old man in an effort to eliminate traces back to himself by concealing the body in the floorboards of the house with his usual "you'll never think I'm crazy after you hear this" bit.  Taking a step back to look at that...he is literally telling us that he is not crazy because he killed his neighbor and then so carefully and deliberately covered up the crime with meticulous effort and, as he thinks, sheer brilliance.  In the very beginning of the story, the narrator also opens with a disclaimer imploring us that he is not crazy for having killed his neighbor.  He assures us that he has every righteous reason to kill him, though he himself acknowledges that he actually had no reason, no personal problem with the man, other than his somewhat excessively creepy eye.  Thus, his own argument is fundamentally flawed, and I think we can say definitively that he is mentally unstable.  I also think it is clear that the guy thinks about EVERYTHING way too much...having to kill someone because their eye bothers you so much?  Seriously, you're going to have to do a lot of thinking to get to that level of "bothersome."  And similarly, it would require a lot of thinking to develop such outrageous theories of self-righteousness that he outlines for us.  This guy may or may not be too smart for his own good, but he definitely thinks too hard and has too much time on his hands.  Moving on to the end of the story...It does seem pretty clear to me that the heart wasn't actually beating (though this is never explicitly stated; quite the contrary, in fact), but rather all just in the killer's head.  We know that he thinks too much, and this definitely looks like a classic symptom of that.  Combine that with the fact that the officers in the room with the killer show no signs of hearing anything, and, of course, the natural impracticality of the heart of a deceased person continuing to beat, and the reality of the sound our killer thinks he is hearing starts to become pretty doubtful.  However, since it was all in his head, this does clearly evidence that the killer is experiencing at least some guilt, so that suggests that though he may be generally bad by nature there is still at least some good to him.  This, perhaps, represents Poe's view of humanity in general.