How, then, am I mad? Observe how calmly I can tell you the whole story.
One of his eyes resembled that of a vulture—a pale blue eye, with a film over it. Whenever it fell upon me, my 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 forever.
I dismembered the corpse. I cut off the head and the arms and the legs. I then took up three planks from the flooring of the chamber and deposited all between the scantlings.7 I then replaced the boards so cleverly, so cunningly, that no human eye—not even his—could have detected anything wrong.
This part of the story is important because we learn why we sets out to kill the old man.
Why would they not be gone? I paced the floor to and fro with heavy strides, as if excited to fury by the observation of the men—but the noise steadily increased. "VILLIANS!"
This is important to the story because of the strategies he uses to kill the old man.
With a loud yell, I threw open the lantern and leaped into the room. He shrieked once—once only. In an instant I dragged him to the floor and pulled the heavy bed over him.
This is important to the story because it truly shows how insane the narrator is really is. Proving the exact opposite as his claim that he isn't insane.
This shows that after he killed the old man and the police came to investigate a scream he had a panic attack or felt guilty about killing the old man .