Metaphor in The Cask of Amontillado

Poe uses metaphors to emphasize the ironic conclusion of the story. The vault in which Montresor traps Fortunato is an extended metaphor for the cask that contains the Amontillado, while Fortunato becomes a metaphorical symbol for the wine; Fortunato is symbolically encased in the very thing he sought.

The Cask of Amontillado 1
"I plastered it up..."   (The Cask of Amontillado)

Poe seems to have created an extended metaphor where the vault represents the cask and Fortunato represents the Amontillado. In the end, Montresor places the final stone to lock Fortunato in the vault forever, just as he would use a keystone to seal Amontillado in a cask. Thus, the figurative Cask of Amontillado becomes the literal tomb of Fortunato.