Act I, Scene I
Sailors try to keep a ship from running aground on the rocks in a stormy sea. The passengers are Alonso, the King of Naples, Alonso's son Ferdinand, Alonso's brother Sebastian, Alonso's advisor Gonzalo, and Antonio. The boatswain says that even kings cannot "command these elements" of wind and water, and tells Antonio and Sebastian that they can either "keep below" or help the sailors. The noblemen take offense at being ordered around by a mere sailor, and both show a mean-tempered streak in this encounter. Suddenly, a panic seizes the sailors, and they declare "all lost," surrendering themselves, and their ship, to the vicious storm. Antonio and Sebastian also fear the worst, and go below to say goodbye to the king, Alonso.
Act I, Scene 2
Prospero and his daughter Miranda are the focus of this scene, and from Miranda's first speech it becomes clear that the storm in the previous scene was somehow caused and controlled by Prospero. Miranda is concerned that good men were lost in the wreck, but Prospero assures her that it all went to plan, and no men were harmed. Prospero explains his motivations for causing the storm by telling her his history with the nobles aboard the ship; he reveals to Miranda that Antonio is his brother, and that he was once the rightful Duke of Milan, a position Antonio now holds. Antonio usurped Prospero's estate and wealth while Prospero became increasingly "rapt in secret studies" and oblivious to his brother's machinations; and in order to take Prospero's title as well, Antonio arranged to have his brother Prospero and Prospero's daughter Miranda killed secretly. But Prospero is widely known to be a good man, so those charged with his death decide not to kill him, Instead, Prospero and Miranda were set adrift on the open sea in a decayed vessel, and were able to survive off the supplies that the honest councilor Gonzalo arranged for them to have; thus, they landed on the island where they now live.
After Prospero's tale, Ariel, a magical spirit, appears; it becomes clear that she is in Prospero's service, and caused the storm, at Prospero's bidding. King Alonso and company are now "dispersed'bout the isle," and Ariel has made the incident look like a shipwreck. Ariel also expresses her wish to be freed by Prospero, although he rescued her from the nasty witch Syncorax. Caliban, who was Syncorax's son, also makes an appearance; Miranda expresses her strong dislike for him, and he has been reduced to no more than Prospero's slave.
Ferdinand, Alonso's son, meets Miranda, and falls immediately in love with her; this appears to be of Ariel's doing, and part of the carefully-laid plan that she must carry out to win her freedom from Prospero.
Analysis of Act I
The play begins with a pair of contrasting scenes; one showing men who are helpless against the storm they believe to be nature's wrath, and one showing the storm itself to be merely the work of an illusionist, trying to reclaim his place through his magic. In the first scene, the boatswain suggests that men, despite their power, are still subject to nature; "what cares these roarers for the name of king," he asks, when the king's ship is being pummeled by the storm (I.i.16-17). The boatswain's statement makes sense in the context of that scene; however, it becomes ironic in the second scene, when Miranda and Prospero reveal that it was Prospero himself who caused the storm.
Antonio and Sebastian's behavior also reveals the brutish, unkind characteristics that mark them throughout the play; Antonio's depiction in this scene gives credence to Prospero's traitorous depiction of his brother that comes out when he tells Miranda about the wrongs perpetrated against him. The first impression of Gonzalo is not quite as correct as those of Antonio and Sebastian; he abets their affront of the boatswain, and shows little of the honesty or kindness which he exhibits later in the play, or for which Prospero remembers him.
Also, Antonio and Sebastian's diffidence toward the boatswain on account of their status is the first demonstration in the play of social hierarchy, which becomes an important theme. Characters within the work, like Antonio, Sebastian, and even Prospero, depend upon the perpetuation of this hierarchy to give them their power, and only become leaders when those beneath them in station submit to them. Caliban is well aware that Prospero's position depends on Caliban's obeisance, as he says to Prospero, "I am all the subjects that you have"; though it is Prospero's "art" and power, rather than a landed title, that makes Caliban, the natural owner of the island, subordinate.
The nature of power is repeatedly in question in this first act; Prospero believes Antonio's power to be marred by its underhanded acquisition, while Prospero believes his own power to be valid and just because he acquired it through his own knowledge and effort. Prospero reasserts his authority over Ariel, claiming that his pains to free her indenture her to him; and over Caliban too, because the charge of attempted rape takes away his credibility, as far as Prospero and Miranda are concerned. However, Prospero's power is not as justly attained as he would like to believe; he keeps Ariel in unwilling bondage, as Sycorax did, and keeps control of Caliban through threats of his power. Prospero debates throughout the work that his power, which he achieved through oppression, is more legitimate than Antonio's, which he achieved through theft; and it is this value judgment that allows Prospero to cast himself as the victim, and Antonio as the villain, though this case might not be correct.
If Prospero has a mirror in any of the characters, it is Sycorax, whom Prospero repeatedly condemns as a witch. Their histories are remarkably similar; both were banished from their native countries, fled to the island for a new life, and gained control over the spirits on the island. Despite Prospero's dislike for Sycorax (which is curious, considering his only knowledge of her is from Ariel), they are also similar in their failings; they share the same anger, both demand servitude from those who are unwilling, and keep others in control though constant threats. Prospero and Sycorax have the same magical abilities through their mutual claim of Ariel, and share the ability to perform feats of magic through the servitude of Ariel.
Prospero's long speech in scene 2 shows several of the contradictions inherent in Prospero's appearance and nature. Prospero can be empathetic and calm, as shown when he gracefully allays Miranda's fears for the safety of the men; but, he is also angry and vengeful, when he speaks of his past and his brother's alleged treachery. He calls his brother "perfidious," "false," and casts his brother as a villain when telling his history to his daughter. Paradoxically, Prospero also admits that it was his "being so retired" from his duties that "awaked an evil nature" in his brother, and his "trust did beget of [his brother] a falsehood" (I.ii.91-96).
Prospero himself causes events, like the shipwreck, without which the play could not exist; in these powers of manipulation, he performs the functions of the author from within the work. Some essayists have gone as far as to claim that Prospero is a mirror of Shakespeare as a writer because of how he fulfills the author function, though there seems to be little supporting evidence for this claim.
As of the end of Act One, Prospero is the only character who is fully fleshed out. The characters of Antonio and Sebastian have been sketched out; and Ariel, Caliban, and Miranda appear, though their interactions with Prospero do more to further Prospero's characterization than their own. However, in Prospero, more than any other character, key themes come into play, and Act One begins the development of this exceedingly crucial character.