True! Nervous. Very, 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.

It is impossible to say how first the idea entered my brain; but once conceived, it haunted me day and night. Object there was none. Passion there was none. I loved the old man. He had never wronged me. He had never given me insult. For his gold I had no desire. I think it was his eye! Yes, it was! One of his eyes resembled that of a vulture - a pale blue eye, with a film over it. Whenever it fell upon me, by blood ran cold; and so by degrees - very gradually - I made up my mind to take the life of the old man, and thus rid myself of the eye for ever.

Edgar Allan Poe, The Tell-Tale Heart