Symbols in The Cask of Amontillado

Poe uses symbols to implicitly tell the audience more about the characters and their situation. For example, he repeatedly mentions the bells on Fortunato’s jester costume to remind the audience of Fortunato’s foolish nature.

The Cask of Amontillado 3
"the bells jingled...."   (The Cask of Amontillado)

Poe continues to mention the jingling of the bells on Fortunato’s cap in order to remind readers of how Fortunado’s jester costume symbolizes the foolish nature of his character--which has yet to change in the story.

"motley..."   (The Cask of Amontillado)

Poe’s choice to have Fortunato in a jester costume (motley), complete with canonical cap with bells, symbolizes Fortunato’s foolishness: he is easily persuaded to follow Montresor and rarely questions him. As Fortunato continues to be tricked, it is only fitting that he look the part.

"putting on a mask of black silk..."   (The Cask of Amontillado)

Why does Montresor make a point of "putting on a mask of black silk"?