eye" that the narrator believes the old man whom he kills possesses. The narrator's fear is communicated through the emotional reaction theprotagonist has when he sees this "evil eye," as the narrator tells the reader that his "blood ran cold." Here, as in the previous example, the fear of the narrator is communicated through the emotional response that the narrator has when he feels fear. In this case, the sensation of his blood "running cold" when he gazes upon the man's eye signifies the terrible fear that he feels, and that drives him to kill the old man, even though he was pleasant and had done nothing wrong to the narrator. 

The narrator's general attitude of fear and paranoia is suggested by the first lines of "The Tell-Tale Heart" by Edgar Allan Poe. He opens his narrative by stating: 

TRUE! —nervous —very, very dreadfully nervous I had been and am; but why will you say that I am mad?

This tells us two things, first that he is nervous and fearful, and second that among the things he fears is being thought insane. 

The next thing the narrator fears is the old man's eye. Strangely—this narrator is crazy after all—he does not fear the old man himself, who is harmless and with whom he has an apparently friendly relationship. The narrator says of the eye: "Whenever it fell upon me, my blood ran cold."

The narrator is also portrayed as abnormally sensitive to sound and prone to frightening auditory hallucinations. Even when the old man is sleeping, the narrator imagines that he can hear the sound of the old man's heart from across the room, and thinks:

And now a new anxiety seized me—the sound would be heard by a neighbour!

This anxiety about the sound of the heart continues even after the old man is dead and dismembered. The narrator still thinks he can hear a beating heart, and the sound terrifies him.

I'm not entirely sure that the narrator was indeed as careful and cautious as he thinks he is.  In the first paragraph of the story, the narrator admits that his sanity has been called into question.  

". . .very dreadfully nervous I had been and am; 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? Hearken! and observe how healthily --how calmly I can tell you the whole story."

Right away in the opening paragraph you have a narrator that is telling his reader that he hears things from heaven and hell.  The entire sequence reads like he is trying to prove he is not crazy.  It's like he is begging the reader to believe him.  

So when he repeatedly tells the reader how careful he was, I doubt certain parts of it.  But in his mind, he was exceptionally cautious.  

"Then, carefully, I lifted the cloth, just a little, so that a single, thin, small light fell across that eye. "

The narrator describes how he sneaked into his master's room for SEVEN nights in a row and carefully uncovered the eye.  The reader is meant to believe that the repetition of the event shows how careful and patient he was. On the 8th night, he was even more careful.  The narrator says that the hands on the clock moved slower than him.  

"The eighth night I was more than usually careful as I opened the door. The hands of a clock move more quickly than did my hand."

After the narrator kills the old man, he again stresses that he is NOT crazy.  And again, the narrator uses his caution to justify that he is not crazy.  

"So I am mad, you say? You should have seen how careful I was to put the body where no one could find it. "

That paragraph alone uses the word "careful" or "carefully" four times.  He was careful to not let any blood get on the floor.  Careful to pull the floor boards up and careful to put them back.  Careful that nobody could see what was done.  

In the narrator's opinion he was cautious because he was patient, and because he was careful to hide all evidence of the murder.  The only thing he wasn't careful about was his own guilt ratting him out to the police officers.  

The narrator is so determined that he has deluded himself into believing that his mental disease is actually making him more conscious and aware. In fact, his so-called focus is extreme paranoia and anxiety. The narrator claims to love the old man but in his neurosis, he justifies his intention to kill the old man because he cannot stand to be looked at by the man's eye. He justifies this intent to kill based on how determined and focused he is in going about the murder. His mad determination overrides this love he has for the old man. 

You fancy me mad. Madmen know nothing. But you should have seen me. You should have seen how wisely I proceeded --with what caution --with what foresight --with what dissimulation I went to work! 

He is determined to kill only when the old man's eye is open. He returns seven times, sneaking into the man's room, only to retreat because the eye is closed. On the eighth night, he is in the room and the old man wakes up. He remains perfectly still. He takes pride in how slowly and stealthily he opens the lantern to catch a glimpse of the old man's eye. 

The narrator continually tries to convince the reader that he is not mad; rather, he is determined and dedicated to a purpose. "If still you think me mad, you will think so no longer when I describe the wise precautions I took for the concealment of the body." His determination and calculation to carry out and get away with the murder consume him. The twist at the end of the story is that the paranoia shifts (perhaps to guilt or fear) and he abandons his determination to avoid being caught; it would seem that in the end, he is actually determined to be caught by the police.