Why the metaphor of the selfish gene remains a powerful thinking tool. What is the evolutionary purpose of the selfish gene? J. Arvid Ågrenis, a Wenner-Gren Fellow at Harvard University, explores why the gene resists and remains a sharp tool for clear thinking. Here, he looks at how it helps our thinking and structure our thoughts as we take on life's difficulties and can also prompt us to address questions that can be answered empirically. "To me, the gene's-eye view has offered all the drama I need. More practically, the gene's-eye view has persisted for the same reason all good metaphors do, because it aids our thinking as we take on the complexities of the living world. It helps us structure our thoughts, and it prompts us to address questions that can be answered empirically. At their best, metaphors have many things in common with mathematical models in that they help to isolate and examine certain properties of a biological observation."