Is the narrator of "The Tell-Tale Heart" by Edgar Allan Poe mad or clever? I need to find support for both theories based on his thoughts and...

While the narrator of "The Tell-Tale Heart" by Edgar Allan Poe considers himself clever, most readers conclude that he is insane.

The narrator gives several pieces of evidence in favor of his being clever rather than crazy. He begins by stating that he was extremely kind to the old man in the weeks leading up to the murder so that the old man would not suspect his plot. He also describes how he would sneak carefully into the old man's room, making sure not to wake him, and patiently cast a single ray of light on the old man's eye while the man slept, arguing that this patience and self-control are evidences of sanity. After the murder, the narrator claims that he is clever because of his method of disposing of the corpse by dismembering it and hiding it under the floorboards and then carefully replacing the floorboards so no one could see they had been disturbed.

Of course, the narrator really is insane. The first piece of evidence we have for this is his motive for murder:

I loved the old man. He had never wronged me. ... I think it was his eye! yes, it was this! He had the eye of a vulture —a pale blue eye, with a film over it. Whenever it fell upon me, my blood ran cold ...

Sane people do not believe that a perfectly nice old man could have an evil eye necessitating the man's murder. Next, sane people don't spend most of their time trying to convince an audience that they are sane. The narrator's belief that he could hear the heart of a dismembered murder victim beating also indicates that he has lost touch with reality.