When Gatsby was a boy, growing up as Jimmy Gatz in poverty on a North Dakota farm, he dreamed of a better life, a life of glamour and excitement. He worked hard to better himself physically and intellectually. He tried to save money and tried to find a way to acquire the wealth he believed would make his dreams come true. One of the notations in his Hopalong Cassidy book read "[s]tudy needed inventions." Becoming a famous inventor probably seemed one way to escape his circumstances.
After running away from home, Jimmy Gatz creates a new image for himself, sails with Dan Cody for five years, and acquires a certain amount of polish. After returning home from World War I, he goes into business with Meyer Wolfsheim, a gangster, and through this association builds a great fortune in a short period of time. With his money, Gatsby buys a beautiful mansion and surrounds himself with glamorous, expensive possessions. Jimmy Gatz's dream comes true.
However, Gatsby's dream does not. Along the way to wealth, Gatsby's original dream is derailed when he meets Daisy and falls deeply in love. When he loses her, Gatsby becomes obsessed with regaining their relationship. Finding Daisy and marrying her in Louisville ("out of her father's house") becomes his dream; he wants to go back to their original time together and repeat the past. Nick tries to tell him that nobody can repeat the past, but the very idea of that truth astounds Gatsby. Gatsby's dream of Daisy cannot and does not come true, but he dies still believing in it.