What is Gatsby's sense of purpose in The Great Gatsby?Jay Gatsby is motivated by his sense of purpose. Could you explain to me this sense of...

As kmcappello notes, Jay Gatsby is supremely concerned
with living the American Dream.  While working as a janitor, Gatsby is invited aboard a
magnificent yacht; after just a brief glimpse into the life of the yacht's wealthy
owner, Gatsby is determined to have such a life for
himself.

More specifically, Gatsby becomes consumed by his
determination to win the affection of Daisy, a woman he meets in Alabama.  He is
immediately intrigued by Daisy's popularity and wealth, and sets out to be with her. 
However, Gatsby's military obligations require him to spend time abroad, and when he
returns, he learns that Daisy has married Tom Buchanan in Gatsby's
absence.

Gatsby purchases a home in West Egg so that he can
be near Daisy, and he throws frequent and lavish parties there in the hopes that she
might attend.  At one point, Nick notes that Gatsby pursues Daisy like "the following of
a grail," and eventually, Gatsby and Daisy do
reunite.

Though the pair do not end up together, Gatsby's
purpose in life is to attain the American Dream so that he may be with Daisy. 
Impressively, he is not swayed from his path despite the fact that Daisy is with Tom. 
Thus, Jay Gatsby is one of the most persistent, driven characters in American
literature, as his goal in life is to work hard to find happiness and live the American
Dream.