Is the theme explicit or implicit for “the raven” by Edgar Allen Poe

He decided on a raven, which he considered "equally capable of speech" as a parrot, because it matched the intended tone of the poem. Poe said the raven is meant to symbolize "Mournful and Never-ending Remembrance".

I hope this is right.

if this is a true or false question its true

every four years the american people choose a new president, and 1988 is one of those years."