What does the second cat symbolize?

The second cat resembles the first in just about every
detail, including the lost eye. The appearance of the image of the gallows in the cat’s
fur (paragraph 20), which demonstrates the narrator’s increasing perverseness and guilt,
marks a change in the story from realism to symbolism and the story’s preoccupation with
evil and guilt. This tends to open the story up for a more and broader interpretation of
things and events, and lends itself very well to analytical interpretation
and understanding. This section of the story lends itself to wonderful discussions on
whether the black cat was actually there or not.