The Tempest is a very famous play written by William Shakespeare. In act 3, scene 3, Antonio and Sebastian are still contemplating killing Alonso. Alonso is increasingly growing exhausted, which is why Antonio and Sebastian keep plotting his death. However, they are interrupted in their scheming by a strange procession of spirits.
Shortly after, Ariel enters the stage, disguised as a harpy. He speaks to Antonio, Alonso, and Sebastian and accuses them of being the reason Prospero is stranded on the island by saying the three did “supplant good Prospero, / Exposed unto the sea… / Him and his innocent child.” He proclaims that the loss of Ferdinand is the punishment for this: “For which foul deed / The powers… / thee of thy son, Alonso, / They have bereft.”
Therefore, the significance of the harpy scene is the fact that here, we learn why misfortune has come upon Antonio, Sebastian, and Alonso: it is punishment for what they did to Prospero. The audience also finds out what they need to do in order to be able to protect themselves from further misfortune: Ariel announces that they must to show “nothing but hearts' sorrow / And a clear life ensuing.”
Through the appearance of the harpy, Prospero is making his plan clear: he seeks revenge. Ariel, in the shape of a harpy, is meant to represent fate and justice. Through Ariel, Prospero announces that he demands punishment from whom he blames for his misfortune. To him, they are guilty and therefore deserve punishment. By Ariel speaking on his behalf, in the shape of a harpy, Prospero makes his anger sound more like a divine prophecy rather than a plan for personal revenge.