The Tempest, like any complex work of art, has more than one theme. One of its major themes, however, is redemption—particularly redemption through suffering and learning.
The play is difficult to classify, being variously labelled a comedy, a romance, and a "problem play." Another way of looking at it, however, would be as an "after-tragedy." Prospero's story before the play begins satisfies all the requirements of a tragedy listed by Aristotle in the Poetics: a great man falls from a high estate through a tragic flaw. He initially shows arrogance but gains knowledge of himself and the world.
Prospero's fall from the Dukedom of Milan happened before the beginning of the play. His process of gaining self-knowledge is ongoing. As the play progresses, he becomes less irascible and manipulative, to the point where he is ready to leave his exile on the island and become a great man in the world again—though he does not expect to rule long in Milan where, he says, "Every third thought...
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