Caliban the deformed savage on the island from his first appearance in the play is more animal than human. Prospero first refers to Caliban by calling him a, "tortoise" (1.2.318). This sets the tone for Caliban's character in the play as he is labeled as a semi-beast in the play. But interestingly despite Caliban's deformed body and animal like appearance he possess remarkable eloquence that gives him power. Prospero, a renaissance prince even with his velvety language only equals Caliban in eloquence. In some ways this dichotomy between Caliban's appearance in the play and his remarkable gift for language creates a magical and mysterious atmosphere in the play. It complicates the relationship between Caliban and Prospero for although Prospero claims to own his savage his savage speaks not like one who is owned.
Caliban from his first appearance in the play speaks with a remarkable eloquence despite his deformed image, "As wicked dew as e'er my mother brushed/ With raven's feather from unwholsome fen/ Drop on you both!" (1.2.324-326).
These lines show how Caliban speaks in the same eloquent tongue that Prospero speaks with. His lines are long and his words are filled with imagery: "wucked dew", "unwholesome fen", "raven's feather". Caliban doesn't in the play ever seem to be at a loss for words when describing his situation. Later in Act 1 Scene 2 Caliban describes how he once the island was his. Caliban acts like a tour guide for the reader describing the water, berries, toads, and beetles of the island. In this passage through language Caliban is able to once again recreate the past when he was not a slave. Caliban despite his position as a slave to Prospero in the physical world in the world of language, Caliban is Prospero's equal.