It's usually a good rule of thumb in literature that when a first-person narrator assigns himself a virtue, the reader should be instantly suspicious. At the very beginning of "The Tell-Tale Heart," the narrator responds to what are apparently questions about his sanity by saying:
...but why will you say that I am mad? The disease had sharpened my senses--not destroyed --not dulled them. Above all was the sense of hearing acute. I heard all things in the heaven and in the earth. I heard many things in hell. How, then, am I mad?
He insists he is sane because he can "calmly" tell his story. To him, a display of calm is therefore an indicator of sanity. He also names "foresight" and "caution" as attributes of sanity, divorcing these traits from the actual actions he takes, as if calmness, foresight, and caution alone, even if applied to irrational and sociopathic acts, constitute sanity.
Ironically, his opening lines protesting his sanity lead us to strongly suspect from the outset that he...
(The entire section contains 2 answers and 800 words.)