Maybe the most appalling idea in The Great Gatsby is the illusion that the past can be regained. Gatsby tells Nick, “Can’t repeat the past? Why of course you can!” This naively illusory remark is the essence of Gatsby’s tragedy. His entire personality consists of repeating what happened five years ago when Daisy loved him before war and money separated them. But time, Fitzgerald writes, is not so forgiving. Daisy is changed. The world is changed. And Gatsby’s failure to accept this is his ultimate failure. He buys the house across the bay, hosts parties for strangers, and builds his fortune all for a moment that no longer exists. The novel holds out time as a relentless and one way process. The tick of the clock when Gatsby and Daisy reunite, the procession of the seasons from summer into autumn, and even the ruin of the billboard in the Valley of Ashes all help to emphasize the inexorability of change. Gatsby’s mistake is not that he wanted too much, but that he wanted the wrong way around. He gets memory and reality and desire and fate confused with each other. Fitzgerald is satirizing this romantic idealism here and teaching us that idealized past prevents us from being in the present. And finally, Gatsby is a prisoner of nostalgia, and his dream is shattered by the reality of how time gets away. His tragic fate is a caution against the danger of idealizing the past and not letting it go.