It is impossible to sum up the works of Edgar Allan Poe in one simple word, because each of his works cannot be done justice unless looked at and analyzed individually. Poe's works teach us so much about human nature and the complexity of that nature. Perhaps the most poignant of his tales, at least when looking at the dual-nature of humanity, is his short story "The Cask of Amontillado". .
Before one can attempt to understand a work of Poe, its hidden meanings or its significance in respect to understanding human nature, one must first realize that the works of Poe possess a certain ambiguity that I cannot help but believe was intentional on the part of Poe. It is this ambiguity that forces the reader to conjure his own personal interpretations through introspection as well as a complicated journey through the nature of his own humanity and humanity in general.
In "The Cask of Amontillado" Poe presents a character in Montressor whose intentions are the chief source of this signature ambiguity. The reader is led to believe at the beginning of the piece that Montressor's actions are motivated by vengeance. "The thousand injuries of Fortunato I had borne as I best could," states Montressor (the work's narrator) in the opening sentence, "but when he ventured upon insult, I vowed revenge." Well, there it is: personal revenge over an insult, made by Fortunato, on Montressor's family. His motivation is clear, is it not? The answer is that it is, in fact, not clear, as the trained reader of Poe would tell you. A little later on in the story, but still close to the beginning, we read that Fortunato is, for lack of a better term, "new money" (not quoted from the text). We, as readers, never know exactly how Forunato originally (supposedly) insulted Montressor's family's honor, but we do see that Montressor feels an underlying bitterness toward Fortunato. We see this in how Fortunato is described by Montressor.