“Pallas” refers to Pallas Athena, the Greek goddess of wisdom. The bust of Pallas in the narrator’s chamber represents his interest in learning and scholarship, and also can be taken as representing rationality in general and his own rational, sane mind in particular. The Raven, by landing on the bust when it flies into the room, signifies a threat to the narrator’s reason and the ability of rationality to analyze and understand the reasons (if any) behind the Raven’s coming and its message. That the Raven stays on top of the bust of Pallas at the end of the poem, never flitting, suggests the dominance of irrationality and fear over reason in general, and, more particularly, that irrationality has taken up a permanent home in the narrator’s formerly rational mind.
The The Raven quotes below all refer to the symbol of Pallas. For each quote, you can also see the other characters and themes related to it (each theme is indicated by its own dot and icon, like this one: Note: all page numbers and citation info for the quotes below refer to the Signet Classics edition of The Raven published in 2008.).
The timeline below shows where the symbol Pallas appears in The Raven. The colored dots and icons indicate which themes are associated with that appearance.
...overcome by despair, while the Raven “never flitting, still is sitting” on the bust of Pallas. The narrator concludes by saying he continues to live in the bird’s inescapable shadow. (full context)