In the "Merchant of Venice" who is Portia disguised as when she gives her speech about "the quality of mercy"?

Portia is disguised as Balthazar when she gives her speech about "the quality of mercy" in "The Merchant of Venice", a 16th-century play written by William Shakespeare. The speech is a monologue and it occurs during Act 4, Scene 1, set in a Venetian Court of Justice. It is the speech in which Portia (Balthazar) begs Shylock for mercy. It is a plea for mercy in favor of Antonio.

Mercy, Portia as a young Balthazar tells those who would exact justice, “It droppeth as the gentle rain from heaven upon the place beneath.” When mercy is unreservedly dispensed, it becomes “the thronèd monarch better than his crown”; it is “an attribute of God himself.”

Shakespeare has taken this opportunity in his play to remine us that "people are most God-like when they are most merciful".