Keeping in mind that F. Scott Fitzgerald's novel The Great Gatsby is a satire on the American Dream that has been inverted by many in the Jazz Age to the acquisition of wealth and social status without any of the sterling virtues of those immigrants who entered Ellis Island with the ethics of honest hard work, morality, and a sense of family, the theme of happiness assumes illusionary dimensions.
Something in his leisurely movements and the secure position of his feet upon the lawn suggested that it was Mr. Gatsby himself, come out to determine what share was his of our local heavens.
This quote is from the end of Chapter One; Nick is outside watching a cat and then notices Mr. Gatsby with feet planted firmly on his lawn, gazing at the green light. This green light at the end of Daisy's pier represents for Gatsby his happiness. For, in the final chapter, Nick reflects upon this green light as representative of Gatsby's "capacity for wonder," the reflection of a man's dream. And, that Daisy is synonymous with his dream is indicated in Chapter Six when Gatsby first speaks with Daisy, he tells her, "You always have a green light that burns all night at the end of your dock."
In relating the past of Gatsby, the narrator Nick Carraway describes Jay Gatsby as having "reveries" that provided him the tie between his material values and his dreams:
For a while these reveries provided an outlet for his imagination; they were a satisfactory hint of the unreality of reality, a promise that the rock of the world was founded securely on a fairy's wing.
Gatsby's idea of happiness is inextricably tied to material values.
3-4. In Chapter Eight after he has been watching "over nothing" in the moonlight, Gatsby "...was clutching at some last hope...," but he surrenders his visionary hope that has simply been reduced to material gain. Daisy, his object of happiness who conspires with her husband Tom to protect themselves after the car accident in which Myrtle Wilson is killed, has become unworthy of Gatsby:
He must have felt that he had lost the old warm world, paid a high price for living too long with a single dream. He must have looked up at an unfamiliar sky through frightening leaves and shivered as he found what a grotesque thing a rose is and how raw the sunlight was upon the scarcely created grass. A new world, material without being real, where poor ghosts, breathing dreams like air, drifted fortuitously about...like that ashen, fantastic figure gliding toward him through the amorphous trees.
5-6. The illusion of Gatsby's dream of happiness with Daisy is further developed in Chapter Nine. Earlier when Nick warns Gatsby that he cannot repeat the past, Gatsby incredulously replies, "Can't repeat the past? Why, of course you can." He believes firmly he can recapture the past and happiness.
Then, in Chapter Nine, Gatsby recognizes the flaws in his dream that is but illusion:
He had come such a long way to this blue lawn, and his dream must have seemed so close he could hardly fail to grasp it. But what he did not know was that it was already behind him, somewhere in the vast obscurity beyond the city, where the dark fields of the republic rolled on under the night."