One of the major themes in Shakespeare’s The Tempest is Prosperos use of magic and how it affects him and those he interacts with. Although Prosperos magic makes him potentially powerful and terrifying, he generally does not use it to do harm. There are some problems with his character, such as his tendency to assume that what he wants is moral and correct, but overall he comes across as someone who is genuinely interested in everyone’s well-being, as long as they are not completely selfish or malicious.
An interesting aspect of Prosperos magic is that it is both the reason for his losing his kingdom and the way he gains it back again. The problem with his earlier interest in magic was essentially that he was absorbed in it at the cost of his actual duties as duke. He was so busy “being transported / And rapt in secret studies” (I.ii.76-77) that he neglected his people and did not notice his uncles movements. He was, in other words “thus neglecting worldly ends, all dedicated / To closeness and the bettering of my mind” (I.ii.89-90). This neglect is what made his use of magic in the past so dangerous, and it could be true of anything.
In the play itself, however, Prospero has changed. He now has a direct aim with his magic, which is to take back what is righfully his so he can do it right. He is not trying to use his powers to cause harm, but to do his idea of justice. This can be seen in his gladness at Miranda’s and Ferdinand’s falling for one another, which he had tried to arrange but was still unsure of whether they would like one another (III.i.92-96).
Although magic was considered evil in Shakespeare’s time, Prosperos is not, because he is willing to abandon it and still act like a human. He also generally tries to use his magic to do good, such as the way he moves around the different groups on the island until they each get what they deserve. Or at least, what Prospero thinks they deserve. This can be seen in how he is compared to “the foul witch Sycorax” (I.ii.258) who had previously kept Ariel in torment trapped in a pine tree where he did “vent thy groans” because of the agony of his imprisonment (I.ii.280). Prospero, in contrast, has promised to free Ariel when he has served his purpose, something he does in fact do for the spirit at the very end of the play (V.i.317-319).
This is emphasized more fully in the lines which Prospero speaks towards the end of the play, in which he explicitly talks about how he has given up his magic and also suggests the reasons for it a little. He says, to the audience, that he will give up his “so potent art,” which he calls “rough magic” (V.i.50). Ultimately, this giving up of what makes him so powerful is what makes him seem like a decent human being underneath it all.