Why do variations in the nervous system cause changes in behavior?

Can someone explain this to me clearly plz

Time is not always change. time can also mean continuity, and it can mean keeping acknowledged truths in mind despite differences in circumstances.there is no better example of this in things fall apart than the retellings of the proverb about the bird named eneke, the language in both retellings is almost identical despite the length of time that has passed between their repetitions. in comparing the usages of the same proverb, achebe allows his readers to note the similarities and differences between the situations, and he them understand how this story can be applied to their own lives.

What does the candle symbolize in this excerpt from leo tolstoy’s the death of ivan ilyich? “when i am not, what will there be? there will be nothing. then where shall i be when i am no more? can this be dying? no, i don’t want to! ” he jumped up and tried to light the candle, felt for it with trembling hands, dropped candle and candlestick on the floor, and fell back on his pillow. a. ivan ilyich’s shallow lifestyle b. ivan ilyich’s troubled conscience c. ivan ilyich’s murky past d. ivan ilyich’s approaching death