What is the significance of the green light?

The green light is perhaps the most important symbol to Gatsby throughout the film. At the beginning, the green light represents Gatsby's desire to win back Daisy. As it is positioned directly across the harbor from his mansion, Gatsby looks at it longingly as a symbol for his desire to be reunited with the woman he loves. He can see her dock, and he knows she is there, just across the harbor. Both visible and out-of-reach, the green light represents the distance between the two lovers, both emotionally and physically. As the film goes on and Gatsby's romantic dreams fall farther and farther out of reach, we see that the green light symbolizes an even deeper desire in Gatsby to attain the unattainable. The green light, both distant and close, pulsing on and off, symbolizes Gatsby's desire to change his entire narrative, to reinvent his biography, to relive the past, so as to create an idealized and impossible future.