Why does Shylock nurse a grudge against Antonio in The Merchant of Venice?
Shylock is a Jewish usurer who makes profits on his loans, so he resents the merchant Antonio, who lends money interest-free to people, which undercuts Shylock.
How like a fawning publican he looks!
I hate him for he is a Christian,
But more for that in low simplicity
He lends out money gratis and brings down
The rate of usance here with us in Venice.
If I can catch him once upon the hip,
I will feed fat the ancient grudge I bear him (Act I, Scene 3, lines 41-47).
As a Jew in Venice, Shylock is restricted to a certain area of the city called the ghetto, a crowded neighborhood where all Jews are required to live. During the Renaissance, Jews were perceived as a threat to Christians, so they were isolated in this city. There was also resentment toward their skills in medicine and banking, so they were prevented from entering such fields. As a result, Shylock is resentful because he feels he could rise much higher in Venetian society if he were not prohibited from certain opportunities and places, avenues open to someone like Antonio.