If we want to answer the question, how tall can the human species grow, then obviously it is well to pick out the ones who are already tallest and study them. If we want to know how fast a human being can run, then it is no use to average out the speed of the population; it is far better to collect Olympic gold medal winners and see how well they can do. If we want to know the possibilities for spiritual growth, value growth, or moral development in human beings, then I maintain that we can learn most by studying our most moral, ethical, or saintly people.