Discovering Class through Poetry

I was intrigued by Rosalind’s ballade (3.2.84-91) and Celia’s almost-soliloquy (3.2.120-149). I am not sure that I understood what Shakespeare was trying to get across with them. Rosalind and Celia go into a pretty deep discussion about the form of the poetry in Celia’s part. I think it is interesting that Shakespeare would draw attention to his poetry, but I think it also says something about the characters Rosalind and Celia. Aren’t they supposed to be in hiding, acting as though they are not from a well-off family? If so, how would they know something like what Rosalind states, “…for some of them had in them more feet than the verses would bear” (3.2.160-1)?