As the title, the phrase "a dream within a dream" has a special significance to any interpretations of the poem. Poe takes the idea of a daydream and twists it so that the narrator's perception of reality occurs at two degrees of detachment away from reality. Consequently, this reality reflects upon itself through the dream medium, and the narrator can no longer distinguish causality in his perception. By showing the narrator's distress at his observations, Poe magnifies the risks of uncertainty and of the potential changes to his identity. Time is a powerful but mysterious force that promotes cognitive dissonance between the protagonist's self and his abilities of comprehension, and the daydream proves to have ensnared him. Alternatively, the poem itself may be viewed as the outermost dream, where the inner dream is merely a function of the narrator's mind.
These words conclude the novel and find Nick returning to the theme of the significance of the past to dreams of the future, here represented by the green light. He focuses on the struggle of human beings to achieve their goals by both transcending and re-creating the past. Yet humans prove themselves unable to move beyond the past: in the metaphoric language used here, the current draws them backward as they row forward toward the green light. This past functions as the source of their ideas about the future (epitomized by Gatsby’s desire to re-create 1917 in his affair with Daisy) and they cannot escape it as they continue to struggle to transform their dreams into reality. While they never lose their optimism (“tomorrow we will run faster, stretch out our arms farther . .”), they expend all of their energy in pursuit of a goal that moves ever farther away. This apt metaphor characterizes both Gatsby’s struggle and the American dream itself. Nick’s words register neither blind approval nor cynical disillusionment but rather the respectful melancholy that he ultimately brings to his study of Gatsby’s life.