Why does O'Brien relate his experience as a pig declotter? How does this information contribute to the story? Why go into such specific detail?

How do the soldiers' feelings about macbeth in act i differ from their laterfeelings about him in act v? a. in act i, theymere jealous of his rise to power; in act v, they feelsorry for him and the burdens he bears.b. in act i, they think he is a bully; in act v, they believe he will make agood king if given enough time to rule.c. in act i, they think he is brave and honorable; in act v, they think heis an insane tyrant who must be defeated.d. in act i, they are frightened of his fierceness; in act v, they areafraid of what horrible crimes he will commit next.