I think that one overriding theme in both is the desire to match one's internal dreams to the external reality. Tom Ripley recognizes the need to bring reality and his own subjective notion of self together. He sees the gap and chasm that exists between them. In this, part of his motivation is to bring both together. In much the same way, George and Lennie seek to bring together their dream of owning a farm and being economically autonomous with their own reality. In both settings, there is a difference between reality and dreams. Along these lines, I would say that there is an element that shows the death of beauty. When Lennie kills Curley's wife by accident, and when Tom kills Dickie, it is a reflection of how beauty, or someone beautiful, falls victim to the external setting. Similarly, both works show how material reality can be a compelling force in driving individuals. George and Lennie, as well as most everyone in Steinbeck's work, are driven by the need to keep and get more money, an element that is scarce in their own lives. Tom, from modest background, is desirous of wealth and does not want to surrender his own world of privilege and prosperity that drives him to live a double life. In both works, the need to be wealthy from origins that are not motivates the characters.