Hamlet is Shakespeare's most popular, and most puzzling, play. It follows the form of a "revenge tragedy," in which the hero, Hamlet, seeks vengeance against his father's murderer, his uncle Claudius, now the king of Denmark. Much of its fascination, however, lies in its uncertainties.

Among them: What is the Ghost--Hamlet's father demanding justice, a tempting demon, an angelic messenger? Does Hamlet go mad, or merely pretend to? Once he is sure that Claudius is a murderer, why does he not act? Was his mother, Gertrude, unfaithful to her husband or complicit in his murder?

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Putting romance onstage, The Tempest gives us a magician, Prospero, a former duke of Milan who was displaced by his treacherous brother, Antonio. Prospero is exiled on an island, where his only companions are his daughter, Miranda, the spirit Ariel, and the monster Caliban. When his enemies are among those caught in a storm near the island, Prospero turns his power upon them through Ariel and other spirits.

The characters exceed the roles of villains and heroes. Prospero seems heroic, yet he enslaves Caliban and has an appetite for revenge. Caliban seems to be a monster for...