Which charcter grows/develops and matures the most in The Great Gatsby?

Nick is the most dynamic character in the book. In the
beginning, he says that he is admired for his ablility to "reserve judgment," but by Chapter 9,
he unleashes a barrage of scathing judgments on the characters in the book and their careless,
hollow lifestyles. Chapter 9 is, effectively, Nick's chapter. He shines. Even though Gatsby
"represents everything for which [he] has an unaffected scorn" and Nick disapproves of him "from
beginning to end," Nick goes out of his way to handle the funeral arrangements and try to "get
somebody" for Gatsby. Nick, who came to New York in search of his own American Dream and attempts
to pursue wealth as a bond salesman, has witnessed first hand the corruption and decadence
associated with easy money. Now, he wants "no more riotous excursions with privileged glimpses
into the human heart." The last four paragraphs of Chapter 9 illustrate how much he has grown and
learned from the events of the summer of 1922. Ultimately, he learns that although we strive to
move forward, our past is always behind us, beckoning from the perspective of "the dark fields of
the republic" which roll "on under the night."