An allusion, of course, is an indirect reference to a literary work. One of the most famous lines from Hamlet is spoken not by a main character, but by a minor one: Marcellus. The quote is, "Something is rotten in the state of Denmark." Marcellus’s line so important because it shows, without a doubt, that Hamlet’s friends question the honesty of the ghost when it appears to Hamlet. Of course, one of the interesting things to consider within the play is whether the ghost has good or evil intentions.