In The Great Gatsby, Fitzgerald offers up commentary on a variety of themes -- justice, power, greed, betrayal, the American dream, and so on. Of all the themes, perhaps none is more well developed than that of social stratification.
What is a major theme of The Great Gatsby?
Fitzgerald carefully sets up his novel into distinct social groups but, in the end, each group has its own problems to contend with, leaving a powerful reminder of what a precarious place the world really is. By creating distinct social classes -- old money, new money, and no money -- Fitzgerald sends strong messages about the elitism running throughout every strata of society.
America in the 1920s marked a time of great post-war economic growth, and Fitzgerald captures the frenzy of the society well. Although, of course, Fitzgerald could have no way of foreseeing the stock market crash of 1929, the world he presents in The Great Gatsby seems clearly to be headed for disaster. They have assumed skewed worldviews, mistakenly believing their survival lies in stratification and reinforcing social boundaries. They place their faith in superficial external means (such as money and materialism), while neglecting to cultivate the compassion and sensitivity that, in fact, separate humans from the animals.