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Nick is fascinated and repelled at the same time by the guests he meets at Gatsby's party. They are all what New York society would have described as being the in-crowd, the beautiful people who knew who to have a good time and where to gather while having it. However, Nick also found them to be incredibly shallow in their actions and attitudes - they took advantage of Gatsby's hospitality and were more concerned with having a good time than with being kind or thoughtful toward each other.
I was one of the few guests who had actually been invited. People were not invited-they went there...Once there they were introduced by somebody who knew Gatsby, and after that they conducted themselves according to the rules of behavior associated with an amusement park.
Nick attempts to get acquainted with various guests but finds it impossible to sustain a meaningful conversation with any of them due to the combination of liquor, dancing and other activities, and constant interruptions.