When I rephrased the speech between Prospero and Caliban (taken from the Tempest, Act I Scene II) I used the same tenses as used in the play. (simple present to refer to their current speech and past simple to refer to their past relationship). Why do I have to use the simple present in both cases? Thank you.

1) At that time (past action) he loved him back. In his turn (In return for his kidness?)Caliban showed him all the features of the island: the freshwater springs, the saltwater pits, the barren places and the fertile ones.
2) Now (at present) he curses himself for doing that. He wishes he could use all the magic spells of Sycorax against him and plague him with toads, beetles, and bats. He is the only subject Prospero has in his kingdom.
3) Prospero was his first king, and now he pens him up in that cave (he keeps him shut up like a farm animal) and doesn't let him go anywhere else on the island.
4) Prospero calls him a liar, who responds better to the whip than to kindness. (who can be influenced only by punishment and not by kindness).
5) He says that he took good care of him and let him stay in his own hut until he tried to his daughter.
If Prospero hadn't stopped him, Caliban would have filled the island with a race of Calibans.
6) Miranda calls him a horrid slave, who can't be trained to be good, and who is capable of anything evil. In the past she pitied him, worked hard to teach him (how) to speak, and taught him some new thing practically every hour.
7) When he didn't know what he was saying, and was babbling like an animal, she helped him find words to make his point understandable.

Clarify all instances of "he" and "him," etc.

http://grammar.ccc.commnet.edu/grammar/composition/literature.htm --
"Write about literature in the present tense unless logic demands that you do otherwise. (Even though a story is written in the past tense, we say that the main character writes to her brother because she thinks she knows something important. Even though Robert Frost is long gone, we say that Frost suggests or uses or says. And in his poems, we say that a phrase or word suggests or means or implies something (all present tense verbs). However, Frost moved his family to England and he died in 1963, etc.)

In rephrasing the speech between Prospero and Caliban, you have used the simple present tense for both their current speech and their past relationship. The reason for using the simple present tense in both cases is to maintain consistency and clarity in the narrative.

1) In the first sentence, you described a past action of Caliban loving Prospero back. By using the simple present tense, you are narrating this past action as if it is happening in the present moment, which helps to make the storytelling more engaging and immediate.

2) In the second sentence, you describe Caliban's current state of cursing himself. By using the simple present tense, you are conveying his ongoing feeling of regret and wishing in the present moment. This helps to create a sense of continuity and allows the reader to empathize with Caliban's emotions.

3) In the third sentence, you talk about Prospero being Caliban's first king and him being confined to a cave. By using the simple present tense, you are describing these past events from the perspective of Caliban's current situation. This gives a sense of permanence to his confinement and highlights the impact it still has on him.

4) In the fourth sentence, you describe Prospero calling Caliban a liar. By using the simple present tense, you are presenting this speech act as if it is happening in the present moment, emphasizing the ongoing conflict between Prospero and Caliban.

5) In the fifth sentence, you describe Prospero stopping Caliban from raping his daughter. By using the simple present tense, you are narrating this hypothetical situation as if it is happening in the present moment, providing a sense of immediacy and making it more vivid for the reader.

6) In the sixth and seventh sentences, you describe Miranda's past actions of teaching Caliban to speak. By using the simple present tense, you are narrating these events as if they are happening right now, which helps to emphasize the impact of Miranda's efforts on Caliban's ability to communicate.

In summary, using the simple present tense in both cases helps to maintain consistency and immediacy in the narrative, making it more engaging and clear for the reader.