Witnessing a banquet complete with sprites and the shapes of unicorns, Gonzalo says: "If in Naples, I should report this now, would they believe me?" (III.iii.27-28). His sentiments are echoed by reformed King Alonso in his final word on Prospero's island and magical art:

This is as strange a maze as e'er men trod;
And there is in this business more than nature
Was ever conduct of: some oracle
Must rectify our knowledge.
(V.i.241-244)

In The Tempest illusion competes with reality and wins despite what our minds, and those of its characters, might say. Not only does magic play an instrumental role in the play, the atmosphere of Prospero's Island is in itself magical. The audience cannot trust its senses in the conventional sense of the word trust; it must surrender to its sense and suspend all disbelief.

Consistent with the theme of illusion, the mechanics of The Tempest often turn on mistaken beliefs about what is real: Ferdinand and Miranda mistake each other for super-natural beings; Stephano mistakes Caliban and Jester Trinculo for a two-headed creature; Caliban mistakes Stephano as god. Antonio and his party are mistaken about the death of Ferdinand; Ferdinand is mistaken about his father's death and his sad elevation to being Naples' new king. When Prospero reveals himself to Alonso, "Behold, sir king, / The wronged Duke of Milan, Prospero," a humbled Alonso can only reply "Whe'er thou be'st he or no, / Or some enchanted trifle to abuse me / As late I have been, I not know" (V.i.111-113). At the same time, the theme of illusion as falsehood also has a normative aspect to it, as when Prospero recounts her uncle Antonio's wrongs to Miranda and asks rhetorically, "then tell me / If this might be a brother" (I.ii.118-119).