In "The Cask of Amontillado," Montresor describes his family coat of arms in the following manner: "A huge human foot d'or, in a field azure; the foot crushes a serpent rampant whose fangs are imbedded in the heel."
How does this description serve as foreshadowing in the story, and what do the objects represent?
Montresor has not been telling Fortunato the truth ever since he encountered him on the street. In fact, he has been lying to Fortunato for years. So there is no reason to believe he is telling the truth about his coat of arms. He is probably amusing himself by making up a fanciful coat of arms which would give his intended victim a clue to his intentions if he were not too drunk to understand. He also tells Fortunato that his family motto is
"Nemo me impune lacessit."
To which Fortunato only replies
Montresor is amusing himself at his victim's expense. He feels secure now that he has him underground. He is armed with a rapier and can kill him at any time, while Fortunato's tight-fitting costume shows he is unarmed. It is likely that Fortunato does not even understand Latin. The motto means "No one injures me with impunity." Even a reader who does not know Latin should be able to figure out that "Nemo" means "nobody," that "me" means "me," and that "impune" means "impunity." "Lacessit" is related to English words like "laceration."
Montresor even pretends to be a Mason.
"A sign," he said.
"It is this," I answered, producing a trowel from beneath the folds of my roquelaire.
So the probability that Montresor's grotesque coat of arms and family motto are fantastical inventions adds a comical dimension to their description. Montresor may not even have a coat of arms or a family motto--and Fortunato may be well aware of this. He may be taunting Montresor, adding one more injury to the thousand injuries Montresor has already referred to at the beginning of the narrative. Fortunato says:
"I forget your arms."
Why bring it up at all, especially at this time? They have known each other for years. This seems disingenuous, deliberately intended to embarrass Montressor, who either has no coat of arms at all, or else has one which signifies inferior status and in any case would mark him as an outsider, a nobody in Venetian society. Fortunato obviously has superior social status. Montresor's French name suggests that he is a relative newcomer to Venice. All those bones in the catacombs may not belong to his ancestors but probably belong to the original owners of his palazzo. He may not even own the palazzo but could be renting it. Those old palazzi were run down and could be rented very cheap, as Henry James relates in "The Aspern Papers."
The cask of Amontillado itself is a fiction. Why believe the coat of arms is real? It is too fitting for Montresor's purpose. It would be too coincidental that arms and motto were exactly suited to his feelings and his murderous intentions. He is telling Fortunato that he hates him and plans revenge--but his poor victim is too drunk to understand what he is hearing. Montresor may be describing the coat of arms and the family motto he would like to have. It is doubtful that anybody outside of Fortunato has even heard Montresor's description of his family coat of arms as
"A huge human foot d'or, in a field azure, the foot crushes a serpent rampant whose fangs are imbedded in the heel."
This would suggest to others that Montresor could be dangerous. He has gone to great pains to present himself as friendly, considerate, long-suffering, tolerant, patient, kind--how could he have such a horrible coat of arms? He is preparing to reveal his true self to Fortunato because, as he says,
[A wrong] is equally unredressed when the avenger fails to make himself felt as such to him who has done the wrong.