As we know, Bassanio needs some cash so he can woo Portia in style. We're talking a team of servants, a new set of fancy threads, and plenty of bling to impress the rich heiress. The problem is, Bassanio's broke. His BFF Antonio would personally lend him the dough, but all of Antonio's money is tied up in some risky business ventures involving a bunch of merchant ships. So Antonio suggests that Bassanio borrow money from Shylock, using Antonio's good credit as collateral. Shylock agrees to the loan but asks for a pound of Antonio's flesh as a guarantee. Antonio agrees because he's completely devoted to his friend.
But why a pound of flesh? In case you're wondering how something like this even comes up in a conversation, here's a look at how it goes down:
Go with me to a notary, seal me there
Your single bond; and, in a merry sport,
If you repay me not on such a day,
In such a place, such sum or sums as are
Express'd in the condition, let the forfeit
Be nominated for an equal pound
Of your fair flesh, to be cut off and taken
In what part of your body pleaseth me. (1.3.17)
OK, we've got some serious questions about Shylock's proposal. First, is he really just joking when he says the "forfeit" should be a pound of Antonio's flesh? Here Shylock acts like it's all in good fun ("merry sport"), but later he ends up demanding his bond in a big courtroom showdown (4.1), and nobody's laughing.
You noticed the way Shylock keeps saying "I'll have my bond" over and over again in Act 3, Scene 3, right? The guy would rather have a piece of Antonio (literally) than "thrice" the amount of money he's owed, which suggests that Shylock is a) bloodthirsty, b) vengeful, and c) inflexible.
Second, what the heck does Shylock mean when he says he gets to pick the body "part" for said pound of flesh removal? Literary critic James Shapiro wonders about this, too, and points out how, even though we later learn that Shylock plans to hack into Antonio's "breast" (read: heart), there's a suggestion that Shylock might just like to remove his enemy's private parts. (This interpretation depends on Shakespeare's habit of using "flesh" as a term for "penis," a move he borrowed from the Geneva Bible.)
Why would Shylock want to do this – aside from the fact that he wants to cause Antonio a whole lot of pain? In Blood Relations: Christian and Jew in The Merchant of Venice, Janet Adelman reminds us that "as the potential circumciser of Antonio, Shylock would be merely following in the footsteps of his allegedly bloody-minded ancestors, who were routinely accused of circumcising Christians."
Jews had been exiled from England way back in 1290, so much of how Elizabethans would have thought of Jews was influenced not by reality but by popular imagination. One particular myth that lived on into the 16th century was the supposed Jewish practice of ritual murder, where Jews would kidnap Christian children on Easter and use their blood in ceremonies around the Jewish holiday of Passover. When Elizabethan audiences watched the play, there's no doubt they would think of this legendary (and entirely fallacious) Jewish practice as a justification for why Shylock would want Antonio's flesh, and why he'd be unconcerned about whether Antonio bled to death. This interpretation is bolstered by the fact that Portia, in her defense of Antonio, states that Shylock cannot spill one drop of "Christian blood," which could be an allusion to the supposed rituals.
Another way to think about Shylock's desire for a pound of Antonio's flesh is to consider the circumstances under which Shylock demands his bond. When Shylock hears the news of Antonio's forfeiture, he also learns that his daughter Jessica has run off to marry a Christian. Shylock's response? He says, "I'll plague him [Antonio]; I'll torture him" (3.1.13). Hmm. Is Shylock looking to compensate for the loss of his own flesh and blood (Jessica) by demanding a little bit of Antonio's flesh and blood?
As for Antonio's willingness to part with his flesh, there are all kinds of possible explanations, but you'll have to read "Characters: Antonio" if you want to know what we think about it.