Which common literary theme

- "is not only a luminous passive watcher in the night sky, but it is a powerful force.

it does symbolizes love,   lust   and dreaming and is seen as a power symbolic force that determines and affects human behaviors and reactions.

in the context of the question it does remain you that he events are only taking place at night and the reader of the passage of time."

the novel is told in flashback

edwards uses the phrase "o who can express what the state of a soul in such circumstances is! " in order to illustrate that this type of suffering is unimaginable. the word "express" denoted that the state of a suffering soul is required to be described by any person, but it would not happen because no one can imagine how this suffering is felt.  

-show what might happen if the reader disobeys edwards is not correct because this is described trhough the text, not by the phrase used.

-describe what endless suffering looks and feels like is not correct because this description might be the porpuse of the excerpt provided, not the porpuse of using the phrase during the writting.

-prove that few people have survived limitless suffering is not correct because it is implied that the soul of a person is already suffering and doesn't have any way to escape.