Three of the greatest American novels--Moby Dick; Absalom, Absalom! and The Great Gatsby--can be easily interpreted as variations on a single 'deep' narrative: the failed quest for an obscure object of desire. In the cases of Melville and Fitzgerald, this is quite obvious, while for Faulkner's novel the interpretation would be more complex, as the book contains multiple questers and objects (including Quentin Compson, seeking a truth he can only create in the telling--somewhat like Nick Carraway during his last-page rhapsody, perhaps).
The tragedy of Gatsby, as I reinterpret it now upon my umpteenth reading, lies in the fact that the self young James Gatz creates is a pure subject of desire for a single object. His desire for Daisy is obsessive, fanatical, and as he attempts to mold himself into the object of his (mis)understanding of her desire (like all infatuated lovers, he assumes her desire to be the mirror of his), he creates a self so single-mindedly object-oriented, so inhuman, that it inevitably shatters--not, as Nick thinks, on the brutal hardness of Tom's personality, but on the human complexity and contradictions of Daisy's messy self.
Aside from these more 'theoretical' concerns, it must be noted that Gatsby is, of course, a fantastically well-written and extremely well-constructed novel. (Because it's so often read in U.S. high schools, these qualities are usually taken for granted; they shouldn't be.) The first chapter is a nearly perfect opening: a brief prologue establishes the narrative voice and teases us into desire for the story to come; the next section admirably sets the geographical and social scene; the dinner scene introduces all the major characters and many of their conflicts; and the ending shows us Gatsby as the self he has constructed, a pure subject of pure desire, beckoning toward the desire of his object, willing Daisy to turn her desire permanently his way, like the green light on the end of her dock. This is what nearly perfect narrative fiction looks like. As Hunter S. Thompson, who shared a language and an addiction or two with Fitzgerald, appreciated, The Great Gatsby is a great course in novel-writing. And it's one hell of a lot cheaper than an MFA. One of the book's principal lessons is "shock the formula." One wouldn't guess from Gatsby's opening that this Jamesian / Horatio Alger narrative would transmute into a melodrama of gangsters and bootlegging and multiple killings before modulating into pathos and tragedy. But that's the winding road Fitzgerald speeds us down. After many re-readings one loses the shock of the Fitzgeraldian new, but for its first readers, Gatsby must have been a deeply surprising novel, a high-speed collision of Whartonian rhetoric and Jamesian irony with the blood-drenched gangster stories of the gutter press. It is a measure of Fitzgerald's artistry that he can, with seeming effortlessness, turn such an unlikely collision into a novel both moving and beautiful.