Why Did Montresor Seek Revenge On Fortunato
Why does Montresor seek revenge on Fortunato, and why does he say, "A wrong is undressed when retribution overtakes its redresser"?
At the beginning of the story, Montresor does not provide details or elaborate on specific incidents for why he plots revenge on Fortunato, but does mention that Fortunato had wrong him a thousand times and insulted his family's prestigious name. Montresor then tells the reader that he has plotted revenge for some time and mentions that he must punish Fortunato without being caught. Montresor then says,
"A wrong is unredressed when retribution overtakes its redresser" (Poe, 1).
Essentially, Montresor means that a wrong is not straightened or atoned for when the punishment overtakes the person enacting revenge. Montresor believes that it is essential to avoid being punished while enacting revenge upon a person. As the story progresses, Montresor deceives Fortunato by acting amiably toward him before leading him down into his family's catacombs, where Montresor shackles and buries Fortunato alive. At the end of the story, Montresor reveals that he successfully enacted revenge without being caught and Fortunato has been buried in his catacombs for a half of century.
In Edgar Allan Poe's "The Cask of Amontillado," the narrator, like so many of Poe's narrators, is unreliable in that he does not provide any reason for his revenge other than the vague statement,
The thousand injuries of Fortunato I had borne as I best could; but when he ventured upon insult,I vowed revenge.
Then, ironically, the narrator assumes that readers know him:
You who so well know the nature of my soul, will not suppose, however, that I gave utterance to a threat.
Obviously, then, there is a great deal of ambiguity about Montresor's "revenge" that he feels (1) he must seek and perform with impunity as well as (2) receive acknowlegement of this revenge on the part of the victim. Both of these goals of revenge are attained: Montresor walls in Fortunato in the tomb/catacombs, and Fortunato is well aware of what Montresor has done as he calls to him, asking to be allowed to return to the carnival, and finally crying "For the love of God, Montresor!"
We do not know why Montresor wants to have revenge on Fortunato. We are told that Fortunato has "injured" him in a thousand ways. But we also can see that Fortunato does not fear Montresor or act strange around him. So that implies that Fortunato does not know Montresor is mad at him.
The phrase that you cite means that there you do not really get revenge if you get caught and punished for doing it. So Montresor does not think it is real revenge to kill someone if you get caught and punished for the murder.