During his conversation with Ariel, Prospero mentions the only other inhabitant of the island prior to his and Miranda’s arrival: Caliban. This inhabitant is the son of the witch (or hag) Sycorax, and Prospero describes him as “a freckled whelp” whose shape is not human (line 285). Although the word whelp can generally mean offspring, the word is most often used to refer to the offspring of a wolf or dog. And, so, Prospero is implying that Caliban has brutish or vicious qualities.
After the sorcerer awakens Miranda, the two visit Caliban. Prospero refers to Caliban as “earth” (line 317). Where Ariel is the spirit of the air, Caliban is the spirit of the earth; and he is as earthy and as detestable as his witchy mother Sycorax. Prospero has forced the dark Caliban into his service, and he refers to the witch’s whelp as a “poisonous slave” (line 322: the reasons for Prospero’s harsh language toward Caliban become clear later).
Caliban appears and immediately curses his magical master and his daughter:
As wicked dew as e’er my mother brushed With raven’s feather from unwholesome fen Drop on you both! A southwest blow on ye, And blister you all o’er! (324-27)
Dew or moisture from a fen or marsh is an ingredient in a witch’s potion, and many people believed that winds from the southwest carried the deadly plague. Because of Caliban’s foul curse, Prospero promises to punish the offender by magically giving him painful cramps and stinging pinches during the night. Caliban claims that the island belongs to him.
He also admits that when Prospero first arrived, the magician treated him kindly, instructed him, and gave him refreshing food and drink. Caliban then loved Prospero and showed him all of the secrets of the island. But now Caliban regrets his kindness toward Prospero because Caliban is now his slave and because Prospero keeps him locked up in a rock or cave.
At that point Prospero becomes angry with the ungrateful Caliban, and he reminds the witch’s son (and thus informs the audience at the same time) that Prospero had been nothing but kind to Caliban and treated him like a son until Caliban “didst seek to violate the honour” of his daughter (350-51). Caliban had attempted to rape Miranda, and thus Prospero made the villain his slave rather than his adopted son.
Caliban does not regret his attempt at raping the girl; and he joyfully exclaims that if Prospero had not stopped him, “I had peopled else this isle with Calibans” (353-54). Caliban would like to have many offspring just like himself, and he imagines an entire litter of them coming from the body of Miranda. Prospero knows that Caliban will continue to try to rape Miranda, and so the wizard has no choice but to keep him locked up.
Miranda is also angry with Caliban, for she too had been kind to him and had taught him how to speak.
Prospero commands Caliban to fetch firewood and perform his other chores; and if Caliban refuses, Prospero will punish him with cramps and aches. Caliban obeys because he knows that Prospero is a very powerful wizard who could even enslave his mother’s pagan god Setebos. The line explains why Caliban obeys Prospero, yet it also establishes that Prospero’s powers are equivalent to those of a minor god.