One of the most persistent charges against Shylock was that he was cruel and bloodthirsty. Antonio says in act 4 scene 1 that it is impossible to soften "his Jewish heart." Bassanio constantly calls him a cur and insults him; how can he call Shylock coldhearted when he and many other characters constantly jeer at Shylock. This also added reason for Shylock's revenge. He wasn't a bloodthirsty miscreant, but a Jew fighting for revenge against years of being spet upon, being treated like a dog, being a victim to Christianity. In his "I am a Jew" speech, he gives these precise reasoning, saying "to bait fish withal; if it will feed nothing else, it will feed my revenge" (Act 3, Scene 1). He doesn't seek revenge personally against Antonio, but against the Christians that have jeered at him and his religion for so long. He explains how since he is a human like any other Christian, he may seek revenge like any other Christian has. The constant repetition in his speech is the word: revenge. Shylock is accused of being bloodthirsty and barbarous, when his quest for revenge differed none from the vengeance any other human would seek and deserve.
Another reason Shylock was criticized was for not showing mercy toward Antonio. In no way was Shylock impelled to let Antonio off easily. On the contrary, the agreement had been made very straightforwardly. Shylock says in act 4, scene 1, "Wouldst thou have a serpent sting thee twice?" Shylock uses a