When deciding whether to include a particular piece of information in an academic essay, which key factor comes into play?

Which two parts of this excerpt from mary shelley’s frankenstein reveals information about the setting? (it was on a dreary night of november that i beheld the accomplishment of my toils.) with an anxiety that almost amounted to agony, (i collected the instruments of life around me, that i might infuse a spark of being into the lifeless thing that lay at my feet. it was already one in the morning; the rain pattered dismally against the panes, and my candle was nearly burnt out) when, by the glimmer of the half-extinguished light, i saw the dull yellow eye of the creature open; it breathed hard, and a convulsive motion agitated its limbs. (how can i describe my emotions at this catastrophe), or how delineate the wretch whom with such infinite pains and care i had endeavored to form? his limbs were in proportion, and i had selected his features as beautiful. beautiful! great god! (his yellow skin scarcely covered the work of muscles and arteries beneath; his hair was of a lustrous black, and flowing; his teeth of a pearly whiteness; ) but these luxuriances only formed a more horrid contrast with his watery eyes, that seemed almost of the same color as the dun-white sockets in which they were set, his shriveled complexion and straight black lips.