It's too simple to say that green means leave, but in all the complexity of Gatsby's plans to win Daisy back, it's not wrong to see green light as exactly what it is. Gatsby believes in light and that light is a symbol of his never-ending quest for Daisy's affection. The green-means-go mentality is one close to Gatsby's heart. Even in death and after he had been shot in the heart, the green light still shone as brightly as Gatsby's gaze across the lake from his dock every day. He doesn't say it specifically but it becomes clear to the reader that he is in a state of denial about his future with Daisy, and that the past will never repeat itself.