How did the quote "I go to see a great perhaps" have an impact in Looking for Alaska by John Green? What does it mean for something to impact a novel?

"I go to seek a Great Perhaps" were the last words of Francois Rabelais, a French Renaissance writer and humanist.  The narrator of Looking for Alaska, Miles, is fascinated by the last words of famous people.  One of his dominant character traits is his ability to memorize and take apart these quotes.  Alaska, too, is fascinated by the idea of a "Great Perhaps."  A running theme in the novel is for characters to define the "Great Perhaps" as they see it, and the Great Perhaps is one of the means Miles uses to cope with his grief over Alaska's death.  It's a quote that binds Miles and Alaska together as well as a quote that helps Miles find peace.

Something impacts a novel by giving it more depth and meaning.  In this case, the Great Perhaps is used to explore death and grief and the emotions therein.  The dying words of a real man lend weight to a fictional story, because the emotions within the novel are emotions that everyone will struggle with at some point in their lifetime.