What does Fitzgerald emphasize at the end of Chapter 8?

At the end of Chapter Eight, Wilson seems to be cast as Gatsby's grim double, representing the more menacing aspects of a capacity for visionary dreaming. Like Gatsby, he fundamentally alters the course of his life by attaching symbolic significance to something that is, in and of itself, meaningless. For Gatsby, it is Daisy and her green light, for Wilson, it is the eyes of Dr. T.J. Eckleburg. Both men are destroyed by their love of women who love the brutal Tom Buchanan; both are consumed with longing for something greater than themselves. While Gatsby is a "successful" American dreamer (at least insofar as he has realized his dreams of wealth), Wilson exemplifies the fate of the failed dreamer, whose poverty has deprived him of even his ability to hope.

Gatsby's death takes place on the first day of autumn, when a chill has begun to creep into the air. His decision to use his pool is in defiance of the change of seasons, and represents yet another instance of Gatsby's unwillingness to accept the passage of time. The summer is, for him, equivalent to his reunion with Daisy; the end of the summer heralds the end of their romance.