It is clear that this is another key indication of the kind of character that Montresor is as a narrator. The fact that he has deliberately organised for his home to be empty when he brings Fortunato home speaks of the way in which he is a calculated killer and has deliberately planned to have Fortunato murdered. However, note what he says about his servants and how he achieves the emptying of his house.
Montresor thus seeks to implicitly recognise the human failings of others. He knows that during the time of Carnival, if given the opportunity, his servants would go out and make merry, even if they were told not to. He cunningly uses this understanding of the foibles of human nature to his own advantage, showing his ability to manipulate others and clearly acknowledging his own lack of scruples in doing so. This helps us develop a picture of a character who manipulates others without any feeling of guilt whatsoever so as to accomplish his own purposes.
2. In Edgar Allan Poe's, "The Cask of Amontillado," why is Montresor's revenge justified?
One of the intriguing aspects of "The Cask of Amontillado" is that we do not know, and cannot know, whether Montresor's relentless and horrific revenge is justified.
For example, Montresor establishes the reason for his hatred at the start of the story when he says
The thousand injuries of Fortunato I had borne as I best could, but when he ventured upon insult, I vowed revenge. You, who know so well the nature of my soul, will not suppose, however, that I gave utterance to a threat.
This disclosure tells us something very important about Montresor, specifically, that he is untrustworthy. Apparently, he has been the victim of a serious insult, but rather than address the problem openly--by challenging Fortunato to a duel, for example--he is disguising his feelings.
More important, however, is that Montresor