The authors are clearly scholars in their field of psychology, speaking intelligently on a wide range of psychological concepts. Yet their style remains conversational and easy to understand; it's not written in a way that makes it seem "over your head." Their personal stories are sometimes humorous, often relevant and totally helpful. Their collaboration on this book sparked an interest in reading other books written by McCullough, Sandage, and Worthington. Michael McCullough, Ph.D., is a psychologist and author. He was a research director at the National Institute for Healthcare Research (NIHR) in Rockville, Maryland. He is director of a human evolution and behavior laboratory and professor of psychology at the University of Miami. He wrote: Beyond revenge: the evolution of the forgiveness instinct, forgiving is human: how to put your past in the past.