The green light at Daisy’s dock is a central symbol in the book: it signals Gatsby into the future, away from the cheapness of his affaire with Daisy which he vainly tries to create in the image of his vision

It embodies the profound naiveté of Gatsby’s sense of the future: "Gatsby believed in the green light, the orgastic future that year by year recedes before us." The green light is the symbol of Gatsby faith.