How are the themes of love, possession, and commerce addressed in The Merchant of Venice?
Love is addressed many ways, including love of a parent and a child and romantic love. The issue of Portia's father and the method he used for getting her a husband after his death doesn't sound very loving to our modern ears, and yet he was probably trying to choose a good man - someone who wouldn't be drawn to silver or gold. Portia didn't like this arrangement, yet out of love and respect for her father, she stuck to it. There is also the issue of Jessica's relationship with her father, and her obvious distaste for him. Then consider Shylock's reaction to her leaving - He alternates between mourning for his "daughter" and his "ducats"! Which does he truly love? Also consider the love (passion) Bassanio and Portia feel for each other, as well as that between Gratiano and Nerissa.
Possession is addressed almost the same way as love. In choosing which casket, each suitor is choosing a possession almost more than a potential wife. Jessica steals Shylock's possessions when she runs away from his home. Then, Shylock rejects the possessions offered him (2-3 times the amount of the bond) because what he really wanted was to be able to legally murder Antonio.
Commerce is a device around which everything revolves in this play. Antonio isn't worried about losing his pound of flesh because he's sure his ships will come in. When they don't, his life is almost forfeit. Shylock is more concerned with the loss of his fortune than the loss of Jessica.