Describe symbolism in The Talented Mr. Ripley by Patricia Highsmith

In Chapter Four, Tom's feeling that New York has become unreal, because he will be leaving it soon, symbolizes his attitude towards other people in general. Like many sociopaths, Tom does not really believe that other people exist in the same sense that he does. To him, they all seem to be cardboard cutouts manipulated through a landscape for Tom's benefit. Unable to feel empathy for others, Tom simply uses other people.