The song "Three o"Clock in the Morning" is referenced in chapter six of F. Scott Fitzgerald's The Great Gatsby. At the beginning of this chapter, Nick reveals what he knows about Jay Gatz's past, Gatsby is snubbed by Tom and his elitist friends, and the Buchanans attend one of Gatsby's parties, which Daisy obviously does not enjoy. All of these things demonstrate a certain side of Gatsby that Nick admires and make him think about his friend's unquenchable hopefulness.
Daisy is just leaving the party with her husband when the song is played, and for a moment Nick wonders if the "neat, sad little waltz of that year" might draw her back to Gatsby. The song also makes him think about the "romantic possibilities" implied by the song and so evident in her lover, Gatsby. Nick wonders if the song might be enough to draw Daisy back, but it does not.
Nick now understands that Gatsby is full of hope and has been living on these "romantic possibilities" for most of his life; now he wonders what extraordinary thing might happen next.
What would happen now in the dim incalculable hours?
Perhaps some unbelievable guest would arrive, a person infinitely rare and to be marvelled at, some authentically radiant young girl who with one fresh glance at Gatsby, one moment of magical encounter, would blot
out those five years of unwavering devotion.
Music often has the power to evoke feelings and memories; this song, "Three o'Clock in the Morning," serves as an inspiration for Nick's musings about the possibilities for the two lovers, Gatsby and Daisy.