The excerpt describes the ritual of a man who is spying on an old man at night. We know this because the room is dark and the old man is asleep in his bed. Although the narrator is describing a creepy and scary ritual, he sounds satisfied, and even gleeful. He seems proud of his actions and at his excellent execution. He also argues that the fact that he can act so carefully and effectively shows that he cannot be mad.
I would say the narrator is gleeful even though he is dealing with a delicate situation . The following sentence indicates a gleeful mood "Oh, you would have laughed to see how cunningly I thrust it in!" And then "<span>Ha! would a madman have been so wise as this? " this line also indicates a gleeful mood at his giddy happiness at being so successful as not awakening the old man. </span>
