Nick Carraway is the narrator of William Scott Fitzgerald's novel The Great Gatsby, and serves as our moral compass and guide to the fabulously wealthy and hedonistic society of "West Egg," a noveau riche enclave based on an area of Long Island where Fitzgerald actually lived, and separated by the Valley of Ashes from East Egg, the home of the true social elite, families with inherited money.
Gatsby is a mystery figure at the start of the novel, apparently fabulously wealthy, rumored to have underworld connections, and with a mysterious past. In Chapter 6 of the novel, as Nick is driving with Gatsby into Manhattan Gatsby himself tells Nick of his past, saying that he is also, like Nick, a midwesterner, originally named James Gatz. When, as a teenager, he encountered Dan Cody, a wealthy copper tycoon in Minnesota, he assumed the name Jay Gatsby, became Cody's personal assistant, and was introduced to wealth and society.
Nick reacts to this revelation by thinking about the ways in which Gatsby embodies the American dream of the self-made man:
I suppose he'd had the name ready for a long time, even then. His parents were shiftless and unsuccessful farm people—his imagination had never really accepted them as his parents at all. The truth was that Jay Gatsby of West Egg, Long Island, sprang from his Platonic conception of himself. ... So he invented just the sort of Jay Gatsby that a seventeen-year-old boy would be likely to invent, and to this conception he was faithful to the end. (6.6-7)
Nick's understanding of this image, though, is ambivalent, for he sees in Gatsby's need to remake himself a hollow core, lacking identity and tradition, just like the world of West Egg.