Why do authors use rhetorical devices in essays

Which traits are strongest in your persuasive essay: ideas, organization, voice, word choice, sentence fluency, or conventions?

Why does the author of exploring the titanic give background information about his youth and education? to show his lifelong love for the ocean

Read the following passage: he roamed from chamber to chamber with hurried, unequal, and objectless step. the pallor of his countenance had assumed, if possible, a more ghastly hue— but the luminousness of his eye had utterly gone out. the once occasional huskiness of his tone was heard no more; and a tremulous quaver, as if of extreme terror, habitually characterized his utterance. there were times, indeed, when i thought his unceasingly agitated mind was laboring with some oppressive secret, to divulge which he struggled for the necessary courage. which of the above ideas might be considered foreshadowing? he is wandering all over the chamber his skin tone is really pale his voice is quivering the narrator thinks he is laboring with an oppressive secret