Jessica and Lorenzo were true lover as Jessica left her house and father for him even when she knows that he is christian and her father hates them. Lorenzo also knows that she is a daughter of a cruel person who don't kind on anyone and finding a way to take revenge from his one of the friends i.e., Antonio.
They always give example about the other lover who couldn't get a true lover in their life like Thisbe, Dido and  Medea.
Jessica was annoyed of her father and started hating all the Jews and loved a Christian. 
In the reference Lorenzo say that on this beautiful night Troilus climbed on the wall of the Troy and sighed for Cressida in the greek lamp.
Jessica says that Thisbe saw the lion's shadow and ran away when his lover came he saw her blood stained cloak and thought she is dead so he kill himself and when she returns saw her lovers body she too kills herself. This shows that they both love each other but couldn't get their love alive. Lorenzo and Jessica feels lucky to be united in this life. 
Then they talk about Dido who loves her lover too much but he doesn't he left her and ran away. She gets a deserted love and hold a willow in her hand while standing on sea shore to give signal to her lover to come back to her.
Even in this night Medea gathered herbs for old Aeson to make him young again.
They discuss about all these people because Jessica had became sad as she was listening to the music she tells Lorenzo that she feels sad when ever she hear music. So to distract her mind from their and make her happy Lorenzo starts discussing about all the lovers. This shows that how much they love each other and care about each other.
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