Why is peripeteia important in a literary work?

it motivates the reader to find meaning in a work.
readers like to be surprised.
it prevents the reader from becoming frustrated.
it explains the theme to readers who may have missed it.

Ill she not be here anon? is she not hurrying to upbraid me for my haste? have i not heard her footstep on the stair? do i not distinguish that heavy and horrible beating of her heart? what is the effect of parallelism in this excerpt? it emphasizes usher’s misunderstanding. it emphasizes usher’s love for his sister. it emphasizes usher’s psychological fixation. it emphasizes usher’s melancholy nature.