In chapter six of The Great Gatsby the closing scene is a flashback to Daisy and Gatsby's first kiss as young lovers. Do you find this passage...

There's a melancholy quality to this passage, an ache of sadness communicated through Fitzgerald's prose. What we as readers are hearing is Nick's distillation of what Gatsby told him of that first encounter. Nick describes Gatsby's storytelling as filled with "appalling sentimentality," but manages to preserve for us the essence of Gatsby's thoughts.

We learn that, even from the start, Daisy is, in part, a figment of Gatsby's imagination, a way for him to achieve his dream. Gatsby sees the sidewalk he and Daisy walk on as part of his ambitions, a "ladder" to a secret place above the trees--above the rest of mere humankind--where Gatsby could "suck on the pap of life." So from the start, Daisy is not simply herself but is incorporated into Gatsby's longing for a better life, a longing for the impossible. 

The chief sadness comes in Gatsby's realization that once he consummates his desire and kisses Daisy, nothing will ever be as good as it was in the moments before the kiss. He knew after he "kissed this girl"--not Daisy, but "this girl"-- his "mind would never romp again like the mind of God."

This encapsulates some of the sadness of the novel, in which yearning for the dream is better than achieving the dream, as we see too when Gatsby reunites with Daisy for the first time since 1917, and Nick notes that no matter how wonderful Daisy is, no real person could live up to Gatsby's imaginings.