Fitzgerald uses several symbols to help readers understand his characters, including the green light that helps readers understand Gatsby's inner motivations. Throughout the novel, Gatsby is chasing dreams that are just beyond his reach. He dreams of reuniting with Daisy and starting a life with her now that he is wealthy, but so much time has passed since they were first together that this is just not possible. Daisy is now married to Tom, and although Tom is cheating on her, Daisy will stay with him because they are from the same elite social sphere—one which Gatsby, no matter how wealthy he is, can never join. Despite this, Gatsby still believes wholeheartedly in the possibility his dream, confidently telling Nick that “of course” one can repeat the past.
Gatsby’s constant reaching for his dreams is symbolized by the way he reaches for the green light at the end of Daisy’s dock, which Gatsby can see from his mansion across the bay. The green light burns all night and Gatsby watches it constantly, highlighting his obsession with his dream of being with Daisy. In the end, Nick sums up Gatsby’s story by referring more explicitly to the symbolism of the green light:
“Gatsby believed in the green light, the orgastic future that year by year recedes before us. It eluded us then, but that's no matter — tomorrow we will run faster, stretch out our arms farther…"
This quote makes it clear that the green light represents Gatsby’s optimistic outlook and his determination to one day achieve his dream of fitting into Daisy’s world. Since Gatsby's dream remains unfulfilled at the end of the novel, the green light might also be interpreted more broadly to represent the elusive nature of dreams. The light’s green color is also symbolic of Gatsby’s journey toward wealth. Green is the color of money and thus his fixation with the green light represents his belief that wealth is a way to get anything that one wants.
Another major symbol related to wealth is the Valley of the Ashes. This desolate stretch of land between New York City and West Egg represents the stark contrast between the rich and the poor and shows that the glitzy and glamorous lifestyles of wealthy and privileged Americans—like Daisy and Tom—come at the expense of the poor. The area’s decay mirrors the moral decay of the wealthy characters, who routinely pass through the Valley of the Ashes as they casually travel between their mansions and the city.