A revised and expanded edition of the definitive guide to the Diamond Approach, the modern contemplative practice that integrates psychology and spirituality and emphasizes the importance of self-inquiry. The Diamond Approach has been developed and taught over the last forty-five years by Hameed Ali, who is known chiefly by his pen name, A. H. Almaas. This book, the first to offer a full overview of the Diamond Approach, is now revised and expanded with a new foreword by Almaas, a new preface by the author, and a new chapter that explores the most recent developments in Almaas's teaching and practice methods. Author John Davis offers a rich, compelling introduction to the unique spiritual tradition that philosopher Ken Wilber recommends as "the most balanced of the widely available spiritual psychologies/therapies." Influenced by ancient traditions such as Sufism and Buddhism as well as by modern psychology, the Diamond Approach is particularly well-suited to twenty-first century seekers who embrace both spirituality and science. Beginning with an account of his own work with the Diamond Approach, Davis proceeds to outline the tradition's central practice of Inquiry, a form of open-ended exploration of present-moment experience akin to mindfulness practice. From there, he launches readers into an exploration of metaphysical concepts such as soul, space, Essence, self-realization, and the dimensions of Being. Complex yet concise, profound yet accessible, The Diamond Approach offers readers bold new perspectives on reality and human potential.