Today the expert, the authority, needs to base instruction and information on as much objective fact as possible; and in the absence of research evidence, clinical experience must of course inform opinion, but this carries less weight in modern health care than in the past. As the healing professions move away from authority-based approaches toward evidence-based practice, a merging of what can be shown by research and clinical audit to be safe and effective should take place. What I have tried to do in this book is to explain the various philosophies and methods, to offer what explanations already exist, and so to begin the process that will eventually unite apparently disparate ideas and methods.