Question

Why does Shylock channel his grief over Jessica’s leaving into anger at Antonio?

Answer 1

Shylock channels all his grief of Jessica’s leaving into anger against Antonio, because:

1. Jessica eloped with a Christian despite knowing that her father has often been insulted by Christians. So, he feels that it is the Christians who have made his daughter go against him. The blame is now shared between Jessica and the Christians, and Antonio being one of the prominent Christians, is an appropriate person to direct all hatred towards.
 2.There is very little that Shylock can do to any other Christian. He can only plan to take revenge from Antonio (because of the signed bond), legally and still not be prosecuted for murdering someone.
3. The plot requires Shylock to be extremely motivated to go ahead with his demand of the pound of flesh. Jessica’s leaving her father makes him even more hard-hearted and determined.

Answer 2

Jessica, Shylock's daughter, had fled with Lorenzo as she was ashamed about her father's moneylending and other ways of plying his trade.
When Shylock gets the news of the escape and that his daughter had exchanged his turquoise ring for a monkey, spent eighty ducats in one night and so on, he is in a rage. Tubal, who gave him all this information, apparently heard the rumours in Genoa, but he quickly changes the topic and narrates the miseries of Antonio, another merchant of Venice and one who Shylock considers an arch-rival. So, Shylock's grief and anger over Jessica's escape turns into a seething anger at Antonio, who also owes him money, having taken a loan from the Jew to help a dear friend, Bassanio.