What is the theme of the great gatsby and how is it seen in the characters and in the novels ending?

The theme of The Great Gatsby is the futile pursuit of hopes and dreams. Gatsby had strong, specific dreams about reconnecting with Daisy and taking their life forward from where they had left off. It was his only goal and his only dream, and Fitzgerald makes it clear that this is useless. The ending of the novel shows that happiness and dreams are mostly unattainable, as they act like a boat on the tide, always escaping the grasp of the person reaching out to them. 

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