This book considers the thought and personalities of two popular icons of twentieth century philosophical and psychological thought - Nietzsche and Jung - and reveals the extraordinary connections between them. Through a thorough examination of their work, Nietzsche and Jung succeeds in illuminating complex areas of Nietzsche's thought and resolving ambiguities in Jung's reception of these theories. The inquiry begins with the location and analysis of the role played by opposites in the whole self according to Jung, revealing the full extent of Nietzsche's influence. This rigorous and original analysis of Jungian theory and its philosophical roots, supported by Jung's seminars on Nietzsche's Zarathustra, leads to the development of a fresh interpretation of the theories of both. Finally the shared model of selfhood is put into practice as the personalities of Nietzsche and Jung are evaluated according to the other's criteria for mental health. This demonstration of how our understanding of analytical psychology can be enriched by investigating its philosophical roots will be of great interest to students in psychology, philosophy and religion as well as practising Jungi