In the balcony scene (Act II, Scene 2) of Romeo and Juliet, when Juliet compares Romeo to a rose, what does the "essence of the rose" mean and how does Juliet compare this "essence" to her feelings for Romeo?
In Act II of Romeo and Juliet, Juliet muses alone on her balcony, considering how unessential a name is to what a thing really is, concluding that its essence does not depend upon any name given to it
That which we call a rose
By any other name would smell as sweet. (2.2.45-46)
Likewise, Juliet reasons, a person's name does not define his essence.
So Romeo would, were he not Romeo call'd,
Retain that dear perfection which he owes
Without that title. (2.2.47-49)
Juliet feels that Romeo's passionate love for her is not mitigated by his being a Montague, and had he a different name, Romeo would still be the same person.
Of course, Juliet has greatly simplified the relationship between Romeo and herself, as the reader soon learns. While their erotic love for one another has nothing to do with their names, the life of their love depends greatly upon their being able to construct an existence together that is apart from that of their families who have long been in enmity. And, as the play's action reveals, they are incapable of forming such a life together because Romeo comes into conflict with the Capulets as does Juliet herself.