What's the tone of this passage? "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 eye I had no desire. I think it was his eye! yes, it was this!" from The Tell-Tale Heart.

I'm reposting this, but with more context for people who have not read the story. So basically the narrator is planning on killing the old man because he has a disfigured eye and it annoys him really bad. The narrator may or may not be insane.