Although this magic has given Prospero great power to lead the others on the island, he has done so in the nature of a God. In order for Prospero to become an ideal human leader, he must give up "this rough magic" and consent to allow his power to flow only from the loyalty of his people and those who believe in him.
Prospero’s use of his magic, while it is done at times to indulge himself is also used in some cases for some greater purpose than that which involves others. Even the masque's main objective was to warn Ferdinand and Miranda.
Prospero's magical powers allow him to single-handedly take control of a situation of slowly developing chaos and turn the plot of ‘The Tempest’ back towards comedy. By sheer force he has power over his surroundings, far greater than those of an ordinary human being, it is incontestable, as is the fact that he uses them for good in the course of the play.
But as a final act, Prospero abandons his magic and releases Ariel and Caliban from their servitude. He describes the loss of his magical powers at the beginning of his monologue when he says, “My charms are all o’erthrown, and what strength I have’s mine own, which is most faint.”
In Prospero, by concealing part of the truth at first, Shakespeare does not present us the perfect ruler immediately. Instead, he develops Prospero from a basically good, excessively trustful but flawed man, to tyrannical man, to a man who is willing to forgive. By the end of the play, Prospero indeed combines power over himself with power over the outer world. Although this does put him in an ideal position to lead, Prospero is brought to a point where he develops control over himself, rather than being presented as such a character immediately. Prospero is also consistently self-indulgent and vain. At the beginning of the play, he calls himself "poor man" in his story to Miranda, and answers her question in extremely long-winded fashion, suiting his own wishes rather than hers. Although he says that his only care has been to serve Miranda, the first thing we see after that is Miranda serving him by helping him take his cloak off implying hypocrisy. Although retaining some vanity and therefore he is not perfect, he will certainly act in a manner befitting an ideal leader.
As he speaks of the past, Prospero is no doubt reliving every single detail "in the dark backward and abysm of time". He seems to have vengeance on his mind right now. Old wounds are cruelly re-opened and he re-experiences the bitterness of betrayal by is "false brother" and the pain of what had happened "twelve year since".
The wise Prospero speaks of how he had laid himself wide open to harm in "being transported and rapt in secret studies". "Neglecting worldly ends, all dedicated to closeness and the bettering of his mind" he entrusted Milan into the hands of his treacherous brother and in doing so, "awak'd an evil nature" in his false brother.
Prospero's anger and feelings of vengeance are understandable but we know that "there's no harm done".
After looking at all of the factors that I think make Prospero important in the play, I see him as being even more of an important character. He expresses many varying emotions that are necessary in order to show his importance in the play. We are presented with a multi-faceted Prospero. The avenger, the father, the master, the duke. Can we really define him? Shakespeare leaves that intriguing thought in our minds as we take leave of this account full of "imagistic" qualities and themes.