Through his use of juxtaposition, Fitzgerald contrasts two worlds--East Egg and West Egg, and, consequently, the lifestyles of Daisy and Myrtle,...

Nick first describes the division between East and West Egg in the following way: "Twenty miles from the city a pair of enormous eggs, identical in contour and separated only by a courtesy bay, jut out into the most domesticated body of salt water in the Western hemisphere" (page 5). East and West Egg are identical physically, and the water that separates them, tame in nature, is described as a "courtesy bay" because the two identical areas of land want little to do with each other. In the immoral and snobbish 1920s society that Fitzgerald describes, the old money of the East Egg was not eager to touch the new money of the West Egg, so it's almost as if the bay is doing East Egg a favor by keeping them apart from West Egg. Nick says that the physical similarities between the two eggs "must be a source of perpetual confusion to the gulls that fly overhead" (page 5). However, to the "wingless," by which he means people, the two Eggs are remarkably different. The fact that birds cannot tell them apart means that the differences between the two Eggs are stem from fine distinctions that the snobbish society of the 1920s drew between people like Tom and Daisy, who had inherited wealth, and people like Gatsby and Nick, who didn't. 

In Chapter Two, the land between West Egg and New York City is described as a barren area known as the "valley of ashes" (page 23). As Nick describes it, this is "a fantastic farm where ashes grow like wheat" and where "men...move dimly and already crumbling through the powdery air" (page 23). This is a kind of no man's land where Myrtle Wilson lives at the gas station her husband owns and where "a small foul river" flows (page 24). The imagery describing the valley of ashes is in great contrast to the sparkling waters of East and West Egg, which abut the glistening Atlantic. Instead, the lifeless, ashen world is similar to hell. This landscape represents the barren hopes of working-class people like George and Myrtle Wilson, who simply wait for the passing cars of the rich who travel back and forth from the Eggs to New York City. In the unfair society of the 1920s, they were shut out, physically and financially, from the opulent lifestyle of the rich people who lived in places like the Eggs.

The immorality of the 1920s is reflected in the differences between the two Eggs because old money people like Daisy and Tom don't try to bridge the gap between themselves and others. They rely on the "courtesy bay," which has deeper metaphorical meanings, to keep themselves separate from other people and their troubles. This bay stands for the way in which the old money rich, like Daisy and Tom, don't consider in the ways in which they are connected to other people. For example, Daisy leads Gatsby to think that she is again in love with him, but then she quickly retreats to East Egg and Tom, leaving Gatsby bereft. Tom, for his part, has a meaningless dalliance with Myrtle, who clearly wants Tom to help her escape from the valley of ashes, but he doesn't try. The people of East Egg separate themselves from the needy, much as the society of the 1920s celebrated wealth without truly trying to affect social or economic change in society. Instead, the 1920s celebrated people who could be successful in society, such as the rich, without reforming society to help the poor or otherwise needy.