What does the quote in "Hamlet" act four, scene five, "There's rosemary that's for remembrance. Pray, you love, remember." mean?
There are two possible answers to this question. The first is that it means absolutely nothing. At this point in the play, Ophelia has gone mad. She goes about chanting nursery songs, random tidbits of information, giving people herbs and flowers, and just not making a whole lot of sense. She has been manipulated into a rejection of Hamlet, who made her believe that he truly and deeply loved her, she has been left all alone by her brother as he goes off to pursue his own interests, and, said ex-boyfriend Hamlet has just randomly and violently killed her father. So, she's had some things happen that push her sanity over the edge. So while Hamlet gallivanting about pretending to be mad, Ophelia actually IS mad. The rosemary quote is just one of many nonsensical items that she mumbles about.
The second possible answer is to look deeper into the play and try to attach meaning to what she says. She could be referring to the fact that people need to remember her father; his death was quickly hushed up because Hamlet was the one that did it, and Claudius didn't want a scandal in his kingdom. They quickly bury him and send Hamlet away without even a slap on the wrist. If you look at it from Ophelia's point of view, that's pretty infuriating. So, maybe this is her skewed way of voicing her frustration that no one does seem to remember. So, if you think about what other possible meanings the theme of remembering could have in the play, you could come up with some other interpretations. I hope that helps a bit; good luck!