This book gets my 5-star rating because it made an excellent addition to my understanding of human life and cognition. Andy Clark is remarkably careful and balanced in his approach, while being totally readable and clear. The book is very well-documented, and his claims are firmly grounded in an argument that relies on few assumptions. He's tackling fundamental questions that are similar to those discussed by Daniel Dennet, but Clark's presentation is more careful and complete, while using an attitude that is far less strident.I recommend this book to anyone who wants to understand better the nature of the perceived boundary between individual person, cognition, language, and interaction, and the way these coevolve.My highest rating.