explain the significiance of the green light?

Fitzgerald, a master of symbols, makes the color green significant in his novel:

"The green, introduced first as the light at the end of a dock, has ambivalent interpretations. Green typically is associated with growth, spring, and new life. It signals “Go! Go! Go!” presumably for any generation. It is the color of money. All of these meanings apply in The Great Gatsby. Primarily, it is connected with Daisy, who turns out to be an unworthy dream. Colors, then, not only vivify images and create a picturesque vista for the reader but also facilitate Fitzgerald’s thematic commentary about reality and dreams."

The green light in particular is a sight that makes Gatsby "tremble." For him it is a beacon, a north star that points to his great love, Daisy. In chapter one, it is Nick who sees Gatsby look watch this light and stretch out his arms to it--a gesture full of longing and desire.

Situated at the end of Daisy’s East Egg dock and barely visible from Gatsby’s West Egg lawn, the green light represents Gatsby’s hopes and dreams for the future. Gatsby associates it with Daisy, and in Chapter 1 he reaches toward it in the darkness as a guiding light to lead him to his goal. Because Gatsby’s quest for Daisy is broadly associated with the American dream, the green light also symbolizes that more generalized ideal. In Chapter 9, Nick compares the green light to how America, rising out of the ocean, must have looked to early settlers of the new nation.